30383473 Automotive Aircnditioning Training Manual
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Automotive Air Conditioning
Training Manual
Compiled by David Townley. Illustrated by Dean Tingate & Glen Burchfield
Company Profile Index Full Screen or Toolbar Print Quit
INDEX
Company Profile
Air International was established in 1967 as a private company. The venture was floated to the public in 1982 and merged with Futuris Corporation Limited in December 1990. As the automotive arm of parent Futuris Corporation Limited, the Air International Group of Companies has succeeded in developing substantial markets for automotive, bus and mobile air conditioning and heating systems; specialised heavy duty air conditioning equipment; electronics; heating and refrigeration hoses, metal fabrication; and steering systems.
Air International Group comprises six manufacturing divisions identified by their specific skills and disciplines - Air International Pty Ltd, Steering Systems Australia, Air International Transit, Aim Metals and Hose and Pipe. The Group also has five joint ventures - Shanghai Wanzhong Air International, China; Voltas - AIG Ltd, India; Automotive Climate Systems, United Kingdom, Coachair Thailand, Thailand; and APM Coachair, Malaysia. The company has its head office in Melbourne (Victoria, Australia) and maintains a world wide network of operations.
Australia
International
Air International Pty, Ltd (Head Office, Port Melbourne) 80 Turner Street, Port Melbourne, Vic, 3207 Australia.
China Shanghai Wanzhong Air International Co. Ltd 76 Gui De Road Songjiang 201600 Shanghai Peoples Republic of China
Divisions: Air International Pty, Ltd (Golden Grove) Golden Grove Road Golden Grove, South Australia, 5125 Australia Steering Systems Australia Pty Ltd Golden Grove Road, Golden Grove, South Australia, 5125 Australia AIM Metals Pty, Ltd Golden Grove Road, Golden Grove, South Australia, 5125 Australia Hose & Pipe 80 Turner Street Port Melbourne, Victoria, 3207 Australia
Malaysia APM Coachair Sbn Bhd Lot 3 Jalan Perusahaan Satu 68100 Batu Caves Selangor Darul Ehsan (DE) Malaysia Thailand Coachair Thailand Co. Ltd 147/255-256 Pinkloa-nakornchaisri Road Southern Bus Terminal Bankoknoi, Bangkok 10700 Thailand India Voltas - AIG Ltd, 5/4 Nagar Road, Pune 411 014, India
Air International Transit Pty, Ltd 4 Bachell Avenue Lidcombe New South Wales, 2141 Australia
Air Conditioning Training Manual
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Index
Click Logo at top of any page to return here
☛
INDEX
Main Menu
2
Company Profile
3
Glossary
11
Section (I) Theory
15
Section (II) System Types
25
Section (III) Components
29
Section (IV) Retrofitting
65
Section (V) Equipment
70
Section (VI) Servicing
75
Air Conditioning Training Manual
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Index
INDEX
Section (1) Theory The Four Major Functions
15
Understanding Heat
16
Change of State
19
Pressure & Temperature Relationship
20
The Ozone Layer
21
R134a Properties
22
Principles of Air Conditioning
24
Air Conditioning Training Manual
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Index
INDEX
Section (11) System Types CCTXV with Block Valve
25
CCTXV with Parallel Flow Condenser
26
CCOT with Parallel Flow Condenser
27
CCOT TXV Dual System
28
Air Conditioning Training Manual
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Index
INDEX
Section (111) Components Compressors -------------------- 29 Clutches --------------------------- 34 Lubrication ----------------------- 35 Condensers ---------------------- 36 Foam Seals ----------------------- 37 Condenser Electric Fans ---- 37 Evaporators ---------------------- 38 Thermal Expansion Valves -39 Super Heat ----------------------- 41 Orifice Tubes -------------------- 42
Air Conditioning Training Manual
Filter Drier Receivers -------------------------- 43 Accumulators ------------------------------------- 44 ‘O’ Rings -------------------------------------------- 45 Hoses ------------------------------------------------- 46 Charging Ports ------------------------------------ 47 Wiring A/C systems ----------------------------- 48 Blower Speed Controls ------------------------ 49 Compressor Cycling Control ---------------- 50 Protective Sensors ------------------------------ 54 Temperature Control -------------------------- 60 Mode Control ------------------------------------- 61 Electronic Temperature Control (ECC)- 63 Page 7
Index
INDEX
Section (1V) Retrofitting Introduction
65
Procedures
66
Retro Chart
68
Air Conditioning Training Manual
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Index
INDEX
Section (V) Equipment Charging
70
Combination Units
71
Gauges
72
Recovery & Recycle
73
Vacuum Pump
74
Air Conditioning Training Manual
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Index
INDEX
Section (V1) Servicing Refrigerant Safety------------------------------------------------------------- 75 Leak Detection ---------------------------------------------------------------- 76 Lubrication ---------------------------------------------------------------------- 79 Lubricating Oil ----------------------------------------------------------------- 80 System Flushing --------------------------------------------------------------- 81 Preparation ---------------------------------------------------------------------- 82 Pressure Gauges --------------------------------------------------------------- 83 Evacuation & Charging Procedure ------------------------------------- 84 Thermistor & Amplifier Testing ----------------------------------------- 86 Diagnostics ---------------------------------------------------------------------- 87 Diagnostics Hints -------------------------------------------------------------- 99 Air Conditioning Training Manual
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INDEX
Glossary Air Conditioner: A device used to control the temperature, humidity and movement of air.
Cold: The absence of heat (the lowest possible temperature is -273.15° C below zero (-459.67°F)
Air Pressure: The pressure exerted in every direction at any given point. Normal atmospheric pressure (pressure caused by the weight of the atmosphere) at sea level is 1 BAR (14.5037 psi).
Compressor: A pump used to draw in low pressure refrigerant gas and squeeze it into a high-temperature high-pressure gas. A second purpose of the compressor is to move refrigerant through the system.
Ambient Temperature: The temperature of air around an object; the outside temperature.
Condensing: Gas changing to liquid.
Bar: International metric measurement unit of pressure. Binary Pressure Switch: A pressure activated contact switch with two functions, normally high and low pressure compressor clutch cut off. Blower: A motor and fan that draws in air and forces it through the heater and/or evaporator cores and into the cabin. Boiling Point: The temperature and pressure at which a liquid changes to gas. Bulk Charging: Use of large containers of refrigerant for charging a refrigerant system. Capillary Tube: A hollow tube filled with refrigerant, part of the thermostatic switch or TX valve. Operates the switch or valve via temperature changes on the capillary tube, resulting in refrigerant expansion or contraction. Carbon Dioxide: A colourless, odourless, inert gas that can be used to purge light contaminate (for example, dust) from air conditioner parts. CFM: Cubic Feet per Minute.
Condenser: A heat exchanger that is used to remove heat from refrigerant, changing it from a high-pressure hot gas to a high-pressure warm liquid. Condensing Pressure: Pressure, as read from the gauge at the discharge service valve; pressure from the discharge side of the compressor into the condenser. Contaminants: Anything other than refrigerant or refrigerant oil in the system. Usually means water in the system; when water and R134a mix hydroflouric acid is created (when water and R-12 mix corrosive hydrochloric acid is produced). Cycling Clutch System: A system which controls compressor clutch operation according to changes in the system pressure and evaporator core temperature. Dehumidify: To remove water from the air. Dehydrate (Evacuate): To place a high vacuum in a refrigerant system to remove all traces of wet air. Desiccant: A drying agent used in the receiver-drier to remove water and ensure a dry system. Dichlorodifluomethane: The chemical name of Refrigerant 12.
Charge: The act of placing refrigerant or oil in the air conditioning system. Also a specific amount of refrigerant or oil by volume or weight.
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Glossary
INDEX
Discharge: To bleed the refrigerant from a system by opening a valve or hose connection and letting refrigerant escape from the system. (To be captured for recycling).
Flushing: A process of cleaning out A/C systems with refrigerant to remove heavy contamination. Flushing refrigerant must be collected and recycled.
Discharge line: Connects the refrigerant compressor outlet to the condenser inlet.
Foaming: Bubbles of oil and refrigerant. Foam in the sight glass means a very low refrigerant charge or P.A.G. oil boiling (refrigerant temperature above 70°C).
Discharge Pressure: Pressure of the refrigerant at the discharge side of the compressor; high pressure side. Discharge Service Valve: A valve on the discharge side of the compressor that allows high-side pressure to be checked and other service operations to be performed. Drive Pulley: A ‘V’ or multi ribbed pulley attached to the front of the engine crankshaft. It drives the compressor clutch pulley with a belt. Driven Pulley: A ‘V’ or multi ribbed pulley attached to the compressor. Duct: A passageway for the transfer of air from one point to another. Evacuate (Dehydrate): To place a vacuum inside a refrigerant system to remove all traces of moisture. Evaporate: Liquid changing to gas. (Change of state) Evaporator Coil: A component in which the liquid refrigerant changes to a gas as it absorbs heat from the air. Expansion Valve: A device that regulates the flow of refrigerant through the evaporator to control temperature. Flooding: A condition caused by too much liquid refrigerant going into the evaporator; usually caused by an expansion valve that is stuck open.
Air Conditioning Training Manual
Freeze-Up: Ice forming at the expansion valve orifice or the evaporator. Head Pressure: Refrigerant pressure from the discharge side of the refrigerant compressor to the condenser. See Discharge Pressure. Heater Core: A heat exchanging component in which hot engine coolant flows to heat the cabin or to modulate temperature produced by the air conditioner. Humidity: The amount of water vapour in the air. Hydraulic Lock: Seizing of compressor due to liquid refrigerant in the piston bore of the compressor. Hydrochloric Acid: A highly corrosive substance that forms when water and R-l2 mix in a refrigeration system. Leak Detector: An electronic device or a coloured die used to detect refrigerant leakage in a refrigerant system. Low Head Pressure: High-side pressure that is lower than normal due to a system problem. Low Pressure Switch: Disengages the compressor clutch when the system pressure drops below a preset level.
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Glossary
INDEX
Magnetic Clutch: An electromagnetic coupling device used to engage or disengage the compressor.
Receiver-Drier: A vessel containing desiccant used to absorb moisture, filter contaminants and store refrigerant.
Manifold Gauge Set: A manifold that is complete with gauges and charging hoses and is used to measure or test system pressures.
Refrigerant-11 (R11): A refrigerant that was used for flushing contaminated air conditioner systems. R- 11 is an ozone depleting substance which must not be released into the atmosphere.
Micron: A unit of length equal to one-millionth of a metre. Used to measure vacuum drawn from a refrigerant system by a vacuum pump. 1000 microns = I mm of mercury (mm HG)= 0.03937 inches of mercury (in HG). One inch of mercury equals 25.400 microns.
Moisture Indicator: A device connected in the high-pressure side which indicates how much moisture is in the system. Nitrogen: A colourless, odourless & inert gas that can be used to purge light contaminants (eg Dust from air conditioner parts). Opacity: A condition that is used to describe contamination of refrigerant oil in the compressor. Fresh refrigerant oil is clear; when contaminated, it appears cloudy because of fine particles held in suspension. Orifice: An opening or small passage. Overcharge: Too much refrigerant or oil in the system. Phosgene Gas: Poisonous gas produced when R-12 contacts an open flame or some other source of intense heat. PSIG: Pounds per square inch gauge pressure. Pressure Switch: A pressure activated contact switch that can de-energise the compressor clutch when a higher or lower pressure occurs in the system or at a medium pressure for activation of a radiator or condenser electric fan.
Air Conditioning Training Manual
Refrigerant - 134a (R-134a): The Ozone friendly cooling agent used in automotive air-conditioning systems. Introduced 1993. See Tetrafluoroethane. Refrigerant - 12 (R-12): The Ozone depleting cooling agent used in older automotive air-conditioning systems. Harmful to the environment. R-12 is an ozone depleting substance not to be released into the atmosphere. See Dichlorodifluomethane. Refrigerant Cycle: The complete circulation of refrigerant through an air conditioning system accompanied by change in temperature, pressure and state. Refrigerant Oil: Highly refined oil that is free from contaminants. Used within the A/C system, the oil is available to suit various types of refrigerant and compressors. Relative Humidity: The water content of the air in relation to the total water the air can hold at a given temperature. Resistor: A voltage dropping device, usually wire of different diameters wound into coils, which provides a means of controlling the blower fan speeds. Schrader Valve: A spring-loaded valve, similar to, but not interchangeable with a car or bicycle tyre valve. Located inside the service valve fittings to hold refrigerant in the system. Special adaptors must be used with or within the gauge hoses to depress the shrader valve and allow testing and servicing to take place. Page 13
Glossary Sensor (ECC): A device/transducer that senses air temperature, sunload and controls voltage for the operation of automatic temperature control units. Sight Glass: A window in the liquid line or filter drier used to check the refrigerant charge. (May not be fitted to some R134a systems.) Suction Line: The line connecting the evaporator outlet to the compressor inlet. Suction Pressure: Compressor inlet pressure (the systems low-side pressure).
INDEX
Undercharge: A system with insufficient refrigerant resulting in lack of cooling and possible compressor damage. Vacuum: Refers to pressure that is less than atmospheric pressure. Vacuum Pump: A mechanical device used to evacuate and place a high vacuum (dehydrate) in the refrigerant system. Vacuum Pump Oil: Special water soluble oil used in most vacuum pumps to absorb moisture. Vapour: The gaseous state of a liquid (i.e., water).
Suction Service Valve: A valve on the suction side of the compressor that allows low-side pressure to be checked and other service operations to be performed. Suction Side: The low-pressure area of the system extending from the expansion valve to the compressor inlet. Tetrafluoroethane: Refrigerant R134a. Thermal Protection Switch: A temperature operated switch of the BI-METAL strip design, normally attached to the compressor housing. At a preset temperature the switch opens circuit and de-energises the compressor clutch. Thermistor: A temperature-sensing resistor (NTC) in the evaporator case used to cycle the compressor on and off. Thermostatic Switch: A temperature sensitive switch used to control system temperature by cycling the compressor on and off. May have fixed or variable settings. Trinary Pressure Switch: A pressure activated contact switch with three functions, normally high and low pressure clutch cut off and condenser fan activation at medium pressure.
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INDEX
Theory The Four Major Functions To be effective, the automotive air conditioner must control four (4) conditions within the vehicle interior : It must cool the air
It must circulate the air
It must purify the air
It must dehumidify the air
These functions are essential if passenger comfort is to be maintained when the ambient temperature and humidity are high.
By performing these functions, the air conditioner maintains the body comfort of the passengers.
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INDEX
Theory Understanding Heat What is Heat
When is Heat Hot? When is Heat Cold?
To understand just how an air conditioning system works, we must first understand the nature of heat.
All substances contain heat!.
For a simple definition we may say that heat is energy. The meshing of gears, the turning of wheels cause friction which results in heat. Combustion (fire) gives off heat. The burning of the sun radiates heat to the earths surface. Heat in the correct amount will provide life and comfort. Heat in either extreme - either to much or to little - will be uncomfortable. The control of temperature means the control of comfort.
Something “feels” hot when it is warmer than our own body temperature. When something contains less heat than our bodies, we say it feels cold! Cold is merely the removal of some heat. Science tells us that a measurement called “Absolute Zero” is the point at which all heat is removed from an object (approximately -273°C ). Any substance above this absolute zero temperature retains some heat.
Air conditioning is a method of controlling heat.
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INDEX
Theory Understanding Heat All Substances Contain Heat The average person requires a comfort zone of approximately 21ºC TO 26º C, with a relative humidity of 45 to 50 %. In this temperature and humidity range, we feel most comfortable. All objects within this same range are comfortable to touch.
As the temperature of anything goes above or below this range, we think of it as HOT or COLD.
Heat Measurement A temperature reading gives us the heat intensity of a substance and not the actual quantity of heat. Heat quantity is measured in “KILOCALORIES” (KCAL’s). One KCAL is the amount of heat required to raise the temperature of one kilogram of water one degree Celsius (at sea level ). This quantity measurement is used in air conditioning to describe heat transfer during changes of state.
1 00 KCA L What Causes Heat To Move? Heat always moves from the hotter object to the colder one. Whenever there is a transfer difference between two (2) objects, the heat energy will be transferred from the warmer object to the cooler one until both objects stabilise at the same temperature.
Ambient 25°C
This is know as the law of heat transfer, and is the basis of air conditioning operation. When a hot cup of coffee is set aside for some time, it becomes cold. Heat moves out of the hot (90ºC) coffee and into the cooler (25ºC) surrounding air. In time the coffee will reach the temperature of the surrounding air.
Air Conditioning Training Manual
90°C
25°C
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INDEX
Theory Understanding Heat How does heat get inside a vehicle? When a car is driven or parked in the sun, heat enters the vehicle from many sources. These sources include: ● Ambient air
All of these and other miscellaneous heat sources increase the air temperature within the vehicle. In a high ambient temperature situation, (eg on a 37o C day), the interior of a vehicle left standing in the sun with the windows closed could reach 65-70o C!
● Sunlight ● Engine heat ● Road heat ● Transmission ● Exhaust system
Sunload Sunload Sunload
Engine Heat
Exhaust Heat
Exhaust Heat Road Heat
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INDEX
Theory Changes of State Evaporation
Vapour
➩
Is the term used when enough heat is added to a liquid substance to change it into a vapour (gas). For example, when water is boiled. This condition occurs within the A/C evaporator.
Liquid
Condensation Glass
Liquid
➩
Is the term used to describe the opposite of the evaporation process. If you take a vapour and remove enough heat from it, a change of state occurs. The vapour becomes a liquid. The change of vapour to a liquid is called condensation.
Vapour
➩
This condition occurs within the A/C condenser
Liquid
Freezing Is another change of state. Freezing results when heat is removed from a liquid substance until it becomes a solid. Remember that anything above -273°C still contains some heat. In an air conditioning system freezing must be avoided. Otherwise component damage will occur.
Liquid
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Theory Pressure & Temperature Relationship To increase or decrease the boiling point of a substance, we must alter the pressure on the substance. Increasing the pressure, increases the boiling point.
70 C
To decrease the boiling point, decrease the pressure.
Mt Everest
8848m
100 C
Sea Level
A good example is the automotive cooling system.
110 kPa
The pressure cap keeps the radiator from boiling over by increasing the pressure on the coolant. Example : 110 kPa radiator cap allows the coolant temperature to reach 126°C before boiling.
This chart opposite shows that the boiling point of water can be altered by changing the pressure upon it. As a comparison with the radiator example above.
The substance used in the air conditioning system, called refrigerant, also boils at different temperatures depending on the pressure that it is under.
Air Conditioning Training Manual
BOILING POINT OF WATER PRESSURE ABOVE SEA LEVEL (kPA)
C
PRESSURE ABOVE SEA LEVEL kPA
0
100
82.7
120.1
13.8
103.4
96.5
123.1
27.6
106.8
110.3
126.8
41.4
110.1
55.2
113.4
69.0
116.8
TEMPERATURE O
TEMPERATURE C
O
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INDEX
Theory The Ozone Layer Ozone (O3) is formed in the upper atmosphere (stratosphere), approximately 10 to 50 kms above the earths surface. This layer acts as a shield that protects the earths surface from harmful ultra violet radiation coming from the sun. The chlorine contained in CFC’s rise into the ozone layer and destroys the ozone molecule O3. Depletion of the ozone layer can be catastrophic to human life causing problems such as ●
Skin cancer
●
Eye cataracts
●
Reduced immunity to disease.
●
Damage to crops
●
Reduced aquatic life
Background 1974 - It was first recognised that the use of chloroflurocarbons (CFC’s) was potentially having a detrimental effect on the ozone layer. 1987 - The Montreal protocol was adopted. This protocol called for restrictions on the manufacture and usage of CFC’s to 1986 levels. From 1987 manufacturers could only produce the same quantities as produced in 1986. 1990 - A second Montreal protocol meeting was held and recommended a total phaseout of ozone depleting refrigerant by the year 2000. 1996(Australia) - January no importation or manufacture of CFC’s. - March, No R12 A/C kits to be sold. 2000 - Total phaseout of CFC’s.
OZO NE
R E Y LA
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INDEX
Theory R134a Properties Since 1993 the Australian Automotive Industry has and will continue to use a non-ozone-depleting refrigerant HFC134a (hydroflourocarbon), its chemical name being Tetra Fluoroethane. We commonly refer to this refrigerant as R134a. R134a was selected as a replacement refrigerant for R12 (Dichlorodifluoromethane) because R12 containing chlorine, has a major effect to ozone layer depletion.
becoming a vapour and absorb large quantities of heat from inside the vehicle. This is what creates the cooling effect you feel inside the vehicle. R134a is stored in containers under high pressure. If it is released into the atmosphere, it will boil at -26.3OC.
R134a and water have the same abilities to change state, but R134a can do this more rapidly and at much lower temperatures than water. At anytime above -26.3 O C, R134a will change its state,
NORMALLY NON-FLAMMABLE
ADDS SLIGHTLY TO GLOBAL WARMING .03
OZONE FRIENDLY
MORE HYDROSCOPIC THAN R12
NON TOXIC
Disadvantages SMALLER MOLECULAR SIZE THAN R12
R 134a
Advantages
Recognised OEM Refrigerant
CHANGES STATE EASILY AT LOW TEMPERATURE
SOLUBLE WITH OIL
STAYS AS A LIQUID UNDER PRESSURE
Air Conditioning Training Manual
LOW BOILING POINT
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INDEX
Theory Refrigerant R134a R134a (HFC 134a)
R12 (CFC 12)
Chemical Name Chemical Formula
Tetra Flouro Ethane CH2FCF2
Dichlorodifluro Methane CCL2F2
Ozone Depleting Potential (R11=1) Global Warming Potential Boiling Point
0
1.0
Less than 0.3
3.0
-26.3OC
-29.6OC
4.2 Angstroms
4.4 Angstroms
Chemical Structure Molecular Structure
R134a Temperature/Pressure Data TempOC -46 -38 -34 -30 -26 -22 -18 -14 -10 -6 -2 0 2
Pressure kPa -64 -45 -32 -17 0.3 20 43 69 99 133 171 191 213
TempOC 4 6 8 10 12 14 16 18 20 22 24 26 28
Pressure kPa 236 260 286 313 341 371 402 434 469 505 543 582 623
TempOC 30 34 38 42 46 50 54 58 60 70 80 90
Pressure kPa 666 758 858 966 1083 1210 1347 1494 1571 2004 2520 3133
R12 Comparison - Temperature/Pressure Data Temp OC
Pressure kPa
TempOC
Pressure kPa
TempOC
Pressure kPa
-46 -38 -30 -26 -22 -18 -14 -10
-54 -32 -1 11 32 56 85 116
-6 -2 0 4 8 12 18 26
150 184 207 248 292 344 432 571
30 38 46 50 54 56 60
666 758 858 966 1083 1210 1347
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Theory
INDEX
Principles of Air Conditioning (CCTXV System) High Pressure Side Low pressure R134a vapour entering the compressor is compressed to become high pressure/temperature R134a vapour. This is then circulated along with lubricating oil to the condenser. As the high pressure/temperature vapour travels through the condenser, heat is released to the cooler ambient air passing over the condenser tubes condensing the vapour into a liquid. This high pressure/temperature liquid then travels through the filter drier onto the TX valve where a small variable orifice provides a restriction against which the compressor pushes.
,
Low Pressure Side Suction from the compressor pulls the high pressure/temperature liquid R134a through the small variable orifice of the TX valve and into the low pressure side of the A/C system. The R134a is now under low pressure and becomes a low pressure/temperature vapour where heat from the cabin being blown over the evaporator coil surface is absorbed into the colder low pressure refrigerant. The R134a is then pulled through the evaporator and into the compressor. The A/C cycle begins again as the R134a vapour is compressed and discharged under pressure.
,
Heat Transfer R134a in the LOW PRESSURE side is COLD and can absorb large quantities of heat from the air moving over the evaporator. R134a in the HIGH PRESSURE side is HOT and the cooler ambient air moving over the condenser can absorb heat from it. Summary ● When the R134a pressure is low, the R134a temperature is low.
,,
● When the R134a pressure is high, the R134a temperature is high.
Air Conditioning Training Manual
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INDEX
System Types
CCTXV with : TX Block Valve; Serpentine Condenser; Serpentine Evaporator Note: Temperatures shown are examples only. o
5 c o
30 c
o
60 c
o
0 c
H/P VAPOUR L/P VAPOUR H/P LIQUID
HEAT GIVEN OFF
L/P LIQUID
o
70 c
o
60 c
o
30 c AMBIENT
Air Conditioning Training Manual
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INDEX
System Types CCTXV with : Parallel Flow Condenser; Expansion Valve, Plate and Fin Evaporator
o
5 c o
30 c
o
60 c
o
0 c
H/P VAPOUR L/P VAPOUR HEAT GIVEN OFF
H/P LIQUID L/P LIQUID
o
70 c
o
60 c
o
30 c AMBIENT
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INDEX
System Types CCOT with : Orifice Tube; Accumulator; Parallel Flow Condenser; Plate and Fin Evaporator Note: Temperatures shown are examples only. o
5 c o
30 c
o
60 c
Orifice Tube
o
0 c
H/P VAPOUR HEAT GIVEN OFF
L/P VAPOUR H/P LIQUID
o
70 c
L/P LIQUID
o
60 c
o
30 c AMBIENT
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INDEX
System Types
CCTXV Dual System with: (2) Externally Equalised TX Valves; (2) Serpentine Condensers in series; (2) Serpentine Evaporator in parallel; (2) Electrical Refrigerant Flow Shut Off Valves
Note: Temperatures shown are examples only.
REAR ELECTRICAL SHUT OFF VALVE
FRONT ELECTRICAL SHUT OFF VALVE
o
0 c
o
H/P VAPOUR
70 c
L/P VAPOUR H/P LIQUID L/P LIQUID
o
60 c
o
60 c
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INDEX
Components Compressors General There are various makes and types of compressors used in automotive air conditioning systems operating on R134a. The internal design could be Piston, Scroll, Wobble plate, Variable stroke or Vane. Regardless, all operate as the pump in the A/C system to keep the R134a and the lubricating oil circulating, and to increase the refrigerant pressure and thus temperature. Sanden - Wobble Plate A reciprocating piston, fixed displacement compressor. The pistons are operated by a wobble plate which moves them backwards and forwards in the cylinders. As the front shaft turns the wobble plate angle changes, causing the pistons to move in and out, pulling refrigerant vapour in through the suction side, compressing it and discharging this high pressure vapour into the condenser.
Suction/Discharge Connections Low Pressure Vapour
Piston
Connecting Rod
Wobble Plate
Charge Ports
¢ Q À @ ,
Intake/Discharge Valves Cylinder Head
High pressure Vapour
Air Conditioning Training Manual
Cam Rotor
Clutch Assembly
Page 29
INDEX
Components Compressors Scroll Type - Sanden This compressor uses a unique design with two scrolls, one is fixed and the other is movable, both are inter-leaved. The movable spiral is able to ORBIT or oscillate without actually fully rotating. The movable scroll is connected to the input shaft via an concentric bearing. As the movable spiral oscillates within the fixed spiral, a number of pockets are formed between the spiral. As these pockets decrease in size the refrigerant is squeezed, the pressure increases and is discharged through a reed valve at the discharge port in the rear section of the compressor.
Suction Pressure Area Field Coil
Clutch Front Pressure Plate
Discharge Valve
Clutch Rotor Pulley Discharge Pressure Area
Movable Scroll
Fixed Scroll
Compression Cycle
Air Conditioning Training Manual
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INDEX
Components Compressors Variable Stroke - Harrison V5 The Delphi (Harrison) V5 compressor is a non-cycling variable displacement compressor. The compressor varies displacement to control capacity to meet A/C system demand at all operating conditions. The compressor features a variable angle wobble plate in a five (V5) cylinder axial piston design. Displacement is controlled by a bellows actuated control valve located in the rear cylinder head. This control valve senses and responds to the system suction pressure or A/C system demand. Through regulation of compressor crankcase
pressure, the wobble plate angle, and therefore compressor displacement, is variable. In general, the compressor discharge pressure is much greater than the compressor crankcase, which is greater than or equal to the compressor suction pressure. At maximum displacement, compressor crankcase pressure is equal to the compressor suction pressure. At reduced or minimum displacement, the compressor crankcase pressure is greater than the compressor suction pressure.
A/C Demand Low Reduced or Minimum Displacement
A/C Demand High Maximum Displacement
Control Valve
Wobble Plate (Reduced or Minimum Angle)
Pivot
Wobble Plate (Maximum Angle) Discharge Pressure
Air Conditioning Training Manual
Suction Pressure
Crankcase Pressure
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INDEX
Components Compressors Rotary Vane - Panasonic Rotary vane compressors consist of a rotor with three or four vanes and a carefully shaped rotor housing. As the compressor shaft rotates, the vanes and housing form chambers.
and oil pump are located on the discharge side, so that the high pressure forces oil through the oil pump and then onto the base of the vanes keeping them sealed against the rotor housing.
The R134a is drawn through the suction port into these chambers, which become smaller as the rotor turns. The discharge port is located at the point where the gas is fully compressed.
During idle an occasional vane noise from the compressor may be heard. This is due to the time taken for the lubricating oil to circulate through the A/C system.
The vanes are sealed against the rotor housing by centrifugal force and lubricating oil. The oil sump
Discharge Port
Discharge Valve Clutch Assembly
Oil Pump Vane
Oil Reservoir Rotor Body
Compression Cycle
Air Conditioning Training Manual
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INDEX
Components Compressors and Mount & Drive Mount & Drive
Idler Pulley
Consists of a bracket to mount the compressor to the engine, a belt idler pulley, compressor drive belt and possibly an extra drive pulley for the crankshaft.
A small pulley normally used in conjunction with a belt adjusting mechanism, also used when a belt has a long distance between pulleys to absorb belt vibrations.
Compressor Mount
Drive Pulley
Manufactured of either plate, cast iron, steel or aluminium, this bracket should exhibit excellent noise absorption qualities especially if using a piston type compressor.
Some vehicles do not have an extra pulley to accommodate an A/C drive belt, in these cases an extra pulley is bolted onto the existing crankshaft pulley.
Multiple Belt Drive
Serpentine Belt Drive
Idler Pulley
Poly ‘V’ Groove
‘V’ Groove
Power Steering Pump
Power Steering Pump Idler Pulley
Alternator
Alternator
Compressor Compressor Water Pump Pulley Air Pump
Crankshaft Pulley
Air Conditioning Training Manual
Water Pump Pulley Air Pump
Crankshaft Pulley
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INDEX
Components Clutches Compressor Clutch The clutch is designed to connect the rotor pulley to the compressor input shaft when the field coil is energised. The clutch is used to transmit the power from the engine crankshaft to the compressor by means of a drive belt. When the clutch is not engaged the compressor shaft does not rotate and refrigerant does not circulate, the rotor pulley free wheels. The field coil is actually an electromagnet, once energised it draws the pressure plate towards it, locking the rotor pulley and the pressure plate together causing the compressor internals to turn, creating pressure and circulating refrigerant.
Front Plate
Pulley Retaining Circlip
Adjusting Shim (Front Plate Air Gap)
Pulley
Air Conditioning Training Manual
Pulley Bearing
Field Coil
Page 34
INDEX
Components Lubrication R134a is part of the air conditioners lubrication system. PAG (Poly alkaline glycol) oil is circulated around the A/C system saturated in the refrigerant R134a. Precautions: ●
●
NEVER operate an A/C system without refrigerant as there will be no lubrication for the compressor and internal damage will occur. Use only the specified oil for the A/C system being worked on i.e. A system using a SANDEN swash plate compressor uses SP-20 PAG OIL.
●
Do not allow PAG oil to contact bare skin Flush skin immediately.
●
Do not allow PAG oil to contact paint work - wash immediately.
●
Avoid breathing PAG oil/R134a mixture.
●
PAG oil is highly hygroscopic. Open containers only when ready to use. Cap containers immediately after use.
Sanden Scroll Type Compressor
Nippondenso Vane Type Compressor
Sanden Swash Plate Compressor
Nipondenso Swash Plate Compressor
Harrison Variable Displacement V5 Compressor
Matushita (Panasonic) Vane Type Compressor
R134a - R12 Comparison ● ● ● ● ●
NEVER mix lubricating oils; Use only PAG oils in R134a systems; Use only mineral oils in R12 systems; USE ONLY THE SPECIFIED OIL FOR THE SYSTEM YOU ARE WORKING ON; Avoid contact with bare skin.
Air Conditioning Training Manual
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INDEX
Components Condensers The Condenser function is to act as a heat exchanger and allow heat to flow from the hot refrigerant to the cooler outside air.
Design Types
R134a entering the condenser will be a high pressure high temperature vapour. As the R134a vapour travels through the tubes of the condenser heat is given off to the cooler ambient air, the refrigerant vapour condenses and changes to a liquid state.
This type of condenser consists of one long tube which is coiled over and back on itself with cooling fins added in between the tubes.
At this point a large amount of heat is given off by the R134a. The refrigerant will now be a hot, high pressure liquid.
This design is very similar to a cross flow radiator. Instead of the refrigerant travelling through one passage (like the serpentine type) it can now travels across numerous passages. This will give larger surface area for the cooler ambient air to contact.
Parallel Flow Design (Recommended for R134a)
Parallel Flow
Serpentine Flow IN High Pressure Vapour From Compressor
OUT High Pressure Liquid to Filter Drier
Serpentine
Heat Given off from Refrigerant to cooler surrounding air
Baffles
IN High Pressure Vapour From Compressor
OUT High Pressure Liquid to Filter Drier
R134a - R12 Comparison ●
As R134a operates on higher pressures, less internal flow, restrictive and improved heat rejection condensers are required.
●
Most manufactures select the parallel flow design for this reason.They are approximately 25% more efficient than the serpentine condensers.
Air Conditioning Training Manual
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INDEX
Components Foam Seals These seals are fitted in between the condenser and radiator to prevent the heated ambient air exiting above, below or to the sides of the space in between (normally 25mm) the radiator and condenser.
Without Foam Seals
As ambient air is drawn through the condenser by the condenser or radiator fan, its temperature increases. If gaps are present between the condenser and radiator this heated air can be circulated back through the condenser. This results in the heated, circulated air causing performance and high pressure problems as the system needs to contend with an increase of air temperature.
Condenser Electric Fan
Fan Types
Most vehicles with air conditioning require an electrical fan to assist air flow, either pushing or pulling the air through the condenser, depending on which side of the condenser the fan is placed. The majority of vehicles using R134a require this additional condenser cooling due to the higher operating pressures of R134a. Also most modern vehicles now have smaller front grilles or bumper bar openings. This causes poor air flow conditions especially at idle when A/C performance is limited by the amount of air flow over the condenser.
Conventional
Skew (By reversing the fan blades it can either push or pull the air)
Basic Circuit The condenser fan is operated with the A/C engaged in various ways: ● Medium pressure switch; ● Indirect connection to the compressor clutch; ● Via the Electronic Control Module(ECM); ● Signal from the A/C switch activation.
Compressor Earth Relay 30 Amp Power to Compressor
Earth
Inline 25 Amp Fuse
Earth
R134a - R12 Comparison ●
Increased use (operation time) with R134a systems due to higher refrigerant temperature.
Air Conditioning Training Manual
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Components Evaporators R134a enters the evaporator coil as a cold low pressure liquid. As this liquid passes through the evaporator coil, heat moves from the warm air blowing across the evaporator fins into the cooler refrigerant. This air that has now been cooled is then ducted into the cabin via the blower motor. When there is enough heat to cause a change of state, a large amount of the heat moves from the air to the refrigerant. This causes the refrigerant to change from a low pressure cold liquid into a cold vapour. (Latent heat of evaporation)
Serpentine Evaporator Same design as the serpentine condenser but approximately five times deeper.
Serpentine Evaporator INLET Low Pressure Liquid
As the warmer air blows across the evaporator fins, moisture contained in that air (humidity) will condense on the cooler evaporator fins. Condensed moisture then runs off through the drain tubes located at the underside of the evaporator case. Plate & Fin Laminated Evaporator Similar operation to the parallel flow condenser were the refrigerant has a multi flow pass creating a larger surface area.
OUTLET Low Pressure Vapour
Plate & Fin Laminated Evaporator (Recommended for R134a)
INLET Low Pressure Liquid
Separating Baffles
OUTLET Low Pressure Vapour to Compressor
R134a - R12 Comparison ●
Most manufacturers prefer to use the plate and fin design for R134a because of the 20% performance increase over the serpentine design.
Air Conditioning Training Manual
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INDEX
Components Thermal Expansion Valves Refrigerant flow to the evaporator must be controlled to obtain maximum cooling, while ensuring that complete evaporation of the liquid refrigerant takes place. This is accomplished by the thermal expansion valve (TXV). Pressures in Control As shown in the illustration, the TXV controls the refrigerant flow by using a system of opposing pressures which we will call:
TXV Closed 8. 7. 3. (F1) 2. A
F1 - Temperature Sensing Capillary Tube Sealed tube filled with refrigerant. This refrigerant is also filled above the diaphragm (7). The capillary tube sensing bulb (3) is attached to the evaporator outlet tube surface. F2 - Pressure Compensation Tube This is a hollow tube connected to the evaporator outlet tube and senses the pressure of the R134a refrigerant leaving the evaporator coil. (Other TX valves may not use this tube as pressure is provided internally within the valve). F3 - Pressure Spring This spring (6) is located under the ball valve (5) Operation Open When the evaporator outlet tube temperature increases, the refrigerant (3) in the capillary tube expands, forcing the diaphragm (7) downwards and thus pushing pin (A) also downwards causing the ball valve (5) to move away from the metering orifice (4), allowing more R134a to enter the evaporator inlet side. Closed As the evaporator outlet tube becomes cooler, the refrigerant in the capillary tube (3) contracts. Forces F2 and F3 cause the diaphragm (7) and pin (A) to move upward allowing the ball valve to move towards the metering orifice (4), restricting the R134a flow. The outlet tube gets warmer and the process starts over.
Air Conditioning Training Manual
5. 4. 6. (F3) 9. (F2)
1.
1- From Filter Drier 2. To Evaporator Inlet 3. Capillary Tube 4. Metering Orifice 5. Ball Valve
High Pressure Liquid
6. Spring 7. Diaphragm 8. Refrigerant 9. Pressure Compensating Tube
Low Pressure Liquid
TXV Open 8. 7. 3. (F1)
2. A 5. 4.
6. (F3) 1.
9. (F2)
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Components Thermal Expansion Block Valve The block valve differs from the previously mentioned expansion valve in that it has four passages, although the basic operation is exactly the same. Operation of the block valve is still via refrigerant expansion/contraction within a diaphragm (11), but not sensed through a separate tube (capillary tube). It is sensed by changes in the refrigerant temperature and pressure passing from the evaporator outlet through the block valve. As the refrigerant from the outlet side of the evaporator passes over the sensing element (12), expansion or contraction of the refrigerant takes place causing the activating pin (8) to move the ball valve (6) away or closer to the metering orifice. This allows more or less refrigerant to enter the evaporator coil inlet. Pressures in Control As shown in the illustrations, the block valve controls refrigerant flow by using a system of opposing pressures which we will call: F1 - Temperature Sensing This is a sealed diaphragm and sensor containing refrigerant. As refrigerant leaving the evaporator coil outlet passes over the sensing element (12) the refrigerant (9) above the diaphragm (11) expands moving pin (8) downwards pushing ball valve (6) away from the metering orifice (5). F2 - Pressure Compensation This is a passage (10) in the block valve outlet side where refrigerant can build up under the diaphragm (11) to act as an opposing pressure to help regulate the amount of refrigerant into the evaporator coil inlet side. F3 - Pressure Spring This spring (7) is located under the ball valve (6) and acts as an opposing force trying to move the ball valve towards the metering orifice (12) and to reduce refrigerant flow to the evaporator coil inlet.
Air Conditioning Training Manual
TXV Open 9. F1
11. 10. F2
12.
3.
4.
2.
1.
5. 6. 7. F3 1. From Filter Drier 2. To Evaporator Coil 3. From Evaporator 4. To Compressor 5. Metering Orifice 6. Ball 7. Spring
TXV Closed
8.
8. Activating Pin 9. Refrigerant 10. Pressure Compensation under Diaphragm 11. Metallic Diaphragm 12. Sensing Element High Pressure Liquid
Low Pressure Liquid
9. F1
11. 10. F2
12.
3.
4.
1. 2.
5. 6.
7. F3
8.
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Components Super Heat At a certain point in the evaporator the R134a refrigerant is completely vapourised, after that point any additional heat absorbed by the R134a vapour is described as SUPER HEATED. The value of this SUPER HEAT is the temperature difference above the point at which R134a liquid changes to a vapour.
Actual Temperature = The temperature of refrigerant at the evaporator outlet.
Example
The thermal expansion valve ( TXV ) values are preset at the factory to compensate for the super heat. Ensure when a TX Valve is replaced it is of the type suited to the A/C system.
Calculation For Super Heat
Saturation Temperature = The temperature at which refrigerant in liquid form changes to a vapour at a given pressure.
Actual Temperature minus Saturated Temperature -
10°C
Super Heat =
5°C
5°C
247 Kpa 5°C Saturated Temperature
From FDR
10°C To Compressor 247 Kpa 10°C Actual Temperature
Air Conditioning Training Manual
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Components Orifice Tube (C.C.O.T.) At the orifice tube the R134a is forced to flow through a fine restriction (orifice). This causes a pressure drop and temperature drop in the R134a entering the evaporator. The rate of flow depends on the pressure differential across the restriction. A fine gauze filter is located at the inlet and outlet sides of the orifice tube to filter any contaminates from passing onto the evaporator. Orifice tubes have different size restrictions depending on the A/C system, these different sizes can be identified by the outer plastic tube colour.
Refrigerant Flow Directional Indicator
To Evaporator
Fine Mesh Filter Outlet
Fine Mesh Filter Inlet
‘O’ Rings
From Condenser
Fixed Small Diameter Bronze Tube (Restriction)
Low Pressure Liquid High Pressure Liquid
R134a - R12 Comparison ●
As R134a operates on higher pressures, less internal flow restrictive and improved heat rejection condensers are required.
●
Most manufactures are selecting this parallel flow design for this reason.
Air Conditioning Training Manual
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INDEX
Components Filter Drier Receiver The filter drier acts as a particle filter, refrigerant storage container and most importantly a moisture absorber. Moisture, temperature and R134a causes hydroflouric and hydrochloric acid. The silica gel beads (dessicant) located in the FDR absorb small quantities of moisture thus preventing acid establishment.
From Condenser
To Evaporator
High Pressure Liquid
High Pressure Liquid
Strainer
,, ,, ,, ,, ,, ,,
Most R134a filter drier's have NO sight glass. This is because at approximately 70°C refrigerant temperature the PAG oil will foam giving a false impression of low gas charge. If the Filter Drier Receiver (FDR) does utilise a sight glass ensure correct diagnosis when viewing. NOTE : Ensure the connection indicated with the word “IN” is connected to the condenser outlet.
Desiccant
Strainer High Pressure Liquid
R134a - R12 Comparison ●
R12 FDR’s use XH5 desiccant;
●
R134a FDR’s use XH7 or XH9 desiccant;
●
NEVER use an R12 FDR on a R134a system;
Air Conditioning Training Manual
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INDEX
Components Accumulator (C.C.O.T) The function of the accumulator is to store refrigerant, filter particles, absorb moisture and separate vapourous R134a from liquid R134a. The Normal process of the CCOT system works when R134a leaves the evaporator coil as a mixture of vapour and liquid. This liquid enters the accumulator and falls to the bottom. The vapour rises to the top and continues onto the compressor. The liquid R134a in the bottom of the accumulator gradually vaporizes off. This vapour rises, then pulls into the compressor.
Vapour Pick Up Tube
To Compressor Low Pressure Vapour
From Evaporator Low Pressure Liquid/Vapour
Low Pressure Liquid Desiccant (XH9) High Pressure Liquid Filter (Oil Suction Port)
Liquid
R134a - R12 Comparison ●
Desiccant changed from XH5 to XH9.
Air Conditioning Training Manual
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Components ‘O’ Rings The ‘O’ ring rubber compound used on R134a A/C system joints, fittings and components, is a hydrogenated nitrile butadiene rubber (HNBR) and identified by the colour green. ‘O’ ring lubrication can be carried out using mineral oil. All hoses, tubes and components included in an A/C kit are pre-lubricated, as are the ‘O’ rings supplied as a spare part. Other manufacturers could use ‘O’ rings of a different colour and size. Ensure that only the approved ‘O’ ring is used for the type of system being serviced or repaired.
R12
R134a
R134a - R12 Comparison ●
R12 ‘O’rings coloured black;
●
NEVER use R12 ‘O’rings with R134a as the ‘O’ ring will be damaged owing to the lack of chlorine in R134a;
●
But you can use R134a ‘O’rings in an R12 system.
Air Conditioning Training Manual
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INDEX
Components Hoses OWING TO THE SMALLER MOLECULAR SIZE AND HIGHER OPERATING PRESSURES OF R134a, the refrigerant hose now incorporates a nylon inner lining. This is to reduce the normal refrigerant leakage that would naturally occur through the porosity of rubber hoses . Most R134a hoses have a smaller outside diameter and thinner hose walls to improve flexibility and reduce noise levels within the A/C system. R 12
R 134a
Rubber
Reinforcement
Rubber Nitrile
Rubber
Reinforcement
Nylon Rubber Nitrile
R134a - R12 Comparison ● ● ●
NEVER use new R12 hose (unless of a barrier type) in an R134a A/C system. The PAG oil and hydrogen contained in the R134a causes the normal R12 nitrile hoses to rapidly deteriorate; R12 hoses have normally large outside diameters. this could create higher noise levels; NEW R12 hoses permeate more refrigerant per year than R134a (R12 approx. 28 grams/year).
Air Conditioning Training Manual
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INDEX
Components Charging Ports Charging ports are fitted onto components such as hoses, tubes and filter drier receivers. These charge ports enable the A/C system to be serviced and tested whilst under pressure. Different size ports identify the high and low sides of the A/C system. A plastic cap with a rubber seal, is used to close the charge port opening and avoid leakage.
Most shrader valves will leak slightly, ensure that the plastic protection cap is fitted. Shrader valves designed for R134a must only be used in R134a systems. This is because of the seal material used.
A dedicated design of charging valve has also been developed to suit the R134a charging ports. R134a Charging Port
R134a Quick Coupler
Open
Close
Hand Wheel (Open/Close Shrader Valve Rubber Sealing Washer Top of Cap
Shrader Valve
Charging Port
R134a - R12 Comparison Shut Off Valve
● Protective Cap
R12
Air Conditioning Training Manual
1/4” or 3/16”
R12
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INDEX
Components Wiring A/C System Control/Wiring Layout (Series Connection) Pressure switches are connected in series with the compressor clutch. If an ‘under’ or ‘over’ system pressure occurs the pressure switch will ‘open circuit’ breaking the circuit to the compressor clutch.
i.e. the pressure switches are a closed circuit, the ECM activates a relay by creating an earth and power is supplied to the compressor clutch. Also an RPM increase generally takes place to avoid engine stall whilst at idle.
With electronic fuel injected vehicles the ELECTRONIC CONTROL MODULE (ECM) is usually interconnected into the A/C wiring circuit. When the A/C switch is engaged a request signal is sent to the ECM, if the A/C circuit is intact,
Power
Fuse Low Pressure Switch
A/C Switch
B8 Blower Switch
Thermostatic Switch
High Pressure Switch
ECM
A/C Relay
Thermal Protector
C2 Diode
Compressor Clutch Field Coil
Air Conditioning Training Manual
A/C Relay Energised only if the ECM provides the Earth
Page 48
INDEX
Components Blower Speed Controls Coil Type This blower speed regulator simply consists of coiled wires connected in series. These coiled wires are of varied thickness. The current flows through either one or a combination of all the coils, the resistance of the coil(s) alter the blower speeds.
Coil Type Protective Cage
The highest blower speed when selected is normally from direct battery voltage via a relay. Fan Speed Resistance Coils
Electronic Type Electronic Electronic Modual
The function of the electronic controller is to convert low current signals from the ECM to a higher current, varying the voltage to the blower motor. Blower speeds may be infinitely variable and usually can have up to 13 speeds. This type of speed controller is normally used with the electronic climate control (ECC) system. The highest blower speed when selected is normally from direct battery voltage via a relay.
Heat Sink
Coil Type
Electronic Type IGN 12V
2.
3.
Blower Switch or Control
Speed 1.
+12V
Blower Motor
To Blower Relay Blower Speed 4.
Air Conditioning Training Manual
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INDEX
Components Compressor Cycling Controls Thermostatic Switch (Anti Ice-up Device) The thermostat is connected in series to the compressor clutch. When the temperature of the evaporator coil approaches freezing 0°C, this temperature is sensed by the thermostat capillary tube which is in contact with the evaporator fins. The capillary tube contains refrigerant, which expands or contracts depending on the temperature on this tube. The points inside the thermostatic switch open up when the refrigerant in the capillary tube contracts (sensing a cold evaporator coil) and interrupt the A/C electrical circuit turning the compressor off. When the evaporator temperature rises again to a preset point (4 - 5 °C) the thermostat points then close. The refrigerant in the capillary tube has expanded (sensing a warmer evaporator coil and the electrical circuit is re-established to the compressor clutch.
Switch Point
Bellows filled with Refrigerant
Capillary Tube
Electrical Circuit
Clutch Coil Ground Ground
Ignition Switch
Resistor
Blower Motor
Combination A/C and Blower Switch
Thermostat
Ground
R134a - R12 Comparison ●
No change except for probe location if a different type of evaporator used.
Air Conditioning Training Manual
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INDEX
Components Compressor Cycling Controls Thermistor & Amplifier This has the same function as the thermostatic switch except rather than mechanical action with contact points and capillary tube, the thermistor and amplifier is electronically activated. The thermistor is a sensing probe but unlike the thermostat capillary tube it senses the air temperature coming off the evaporator coil.
Amplifier
Thermistor Electrical wiring containing a sensor which is a NTC Resistor (Negative Temperature Co-efficient). Amplifier A small electronic device containing a circuit board and electrical components. Thermistor resistance is amplified and used to control or switch the A/C clutch on or off.
Thermistor
Economy Mode This function is normally associated with the use of a thermistor amplifier (described above). In economy (ECON) mode the compressor cut out temperature is set higher than in the normal A/C mode. This means the compressor stays on for a lesser time, decreasing engine load and improving fuel economy and engine performance. Centre vent temperatures will also be slightly higher due to the compressor cycling off at a higher evaporator temperature.
A/C / ECON Switches
R134a - R12 Comparison ●
No change except for probe location if a different type of evaporator used.
Air Conditioning Training Manual
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INDEX
Components Compressor Cycling Controls Pressure Cycling Switch - Electrical Some vehicles using the Cycling Clutch Orifice Tube (CCOT) system, utilise a pressure switch located in the low side of the A/C system between the evaporator and the compressor for compressor control. This pressure switch is electrically connected in series with the compressor clutch. Once the low side pressure reaches approximately 200 kPa, the compressor clutch is deactivated by the pressure switch opening. A low side pressure of approximately 200 kPa corresponds to an evaporator coil temperature of approximately + 0. 5°C (above freezing point).
Once the compressor is deactivated the low pressure rises followed by the evaporator coil temperature rising. At a predetermined low pressure point, the pressure switch reactivates the compressor clutch. The evaporator temperature lowers again and the compressor re-engages. NOTE: Normally a low pressure cut off switch is not used with a pressure cycling switch as the pressure cycling switch is located on the low side. It serves as a low pressure cut off also.
AC
High Pressure Switch
Pressure Cycling Switch Compressor Clutch Disengages at approx. 200kpa. Re-engages approx. 350kpa
Air Conditioning Training Manual
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INDEX
Components Compressor Cycling Controls Pressure Control Valve - Mechanical A/C Demand High During periods of moderate to high A/C demand, system suction pressure will be greater than the control valve set point. During these periods, the control valve maintains a bleed from crankcase to suction. Crankcase pressure is therefore equal to suction pressure. The wobble plate angle, and therefore compressor displacement is at its maximum.
A/C Demand Low During periods of low to moderate A/C demand, system suction pressure will decrease to the control valve set point. The control valve maintains a bleed from discharge to crankcase and prevents a bleed from crankcase to suction. The wobble plate angle, and therefore compressor displacement is reduced or minimised. During these periods, displacement is infinitely variable between approximately 5 and 100% of its maximum displacement.
Harrison Variable Stroke Compressor
Discharge Crankcase Valve
Suction Crankcase Valve
From Discharge Chamber
To Compressor Crankcase From Crankcase Chamber
To Suction Chamber
Crankcase Control Valve
Evacuated Bellows
Discharge Pressure
Air Conditioning Training Manual
Suction Pressure
Crankcase Pressure
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INDEX
Components Protection Devices Clutch Diode The clutch coil is an electromagnet with a strong magnetic field when current is applied. This magnet field is constant as long as the clutch is applied. When the power is removed the magnetic field collapses and creates high voltage spikes. These spikes are harmful to the ECM and
must be prevented. A diode placed across the clutch coil provides a path to ground. This diode is usually taped inside the clutch coil connector.
Diode
Thermal Protection Switch
Compressor Clutch
Thermal Protection Switch The thermal protection switch is normally located on the compressor housing. This protection switch is used to prevent compressor damage through internal friction.
Lead Wires Movable Contact
This switch senses the compressor case temperature and once this case temperature reaches a predetermined figure the electrical circuit to the compressor clutch is interrupted. Pin
As the thermal protection switch is connected in series with the compressor clutch once the compressor case temperature lowers to a predetermined figure the compressor clutch is then re-energised.
Fixed Contact Bimetallic Strip
R134a - R12 Comparison ●
Different temperature settings due to higher operating pressures and temperatures.
Air Conditioning Training Manual
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INDEX
Components Protection Devices Refrigerant Pressure Switches Low Pressure - Used to interrupt the electrical circuit to the compressor clutch. If the refrigerant pressure is too low or a problem exists in the A/C refrigerant system. (refer diagram)
R134a Charging Port Refrigerant Pressure Diaphragm
High Pressure - The power supply is interrupted when the refrigerant pressure is too high or a problem exists in the A/C refrigerant system. Contacts Activating Pin
Terminology Binary Switch - High/Low switch.
Compressor Clutch
Power
Trinary Switch - High/Medium/Low switch.
Condenser Fan Control
1770 kpa (example)
Medium Pressure - Used to engage the condenser fan at a pre-determined refrigerant pressure. Example: Condenser Fan high speed activation at 1770kpa refrigerant pressure. These switches can be individual or a combination of the two or even three pressure ranges.
R134a - R12 Comparison - Setting Differences ●
Different high pressure settings due to higher operating pressures and temperatures. R134a System = 3200 kPA (High Pressure) R12 System
= 2760KPA (High Pressure).
Air Conditioning Training Manual
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Components Protection Devices Pressure Transducer The pressure transducer is a sealed gauge reference, capacitive pressure sensor with on board signal conditioning. It provides a 0.5 volt output and requires a 5 volt regulated power supply. In operation the transducer sensor applies pressure via the deflection of a two piece ceramic diaphragm with one half being a parallel plate capacitor. Changes in capacitance influenced by the refrigerant pressure under the ceramic diaphragm are converted to an analog output by the transducers integral signal electronics. The pressure transducer’s electronics are on a flexible circuit board contained in the upper
section of the transducer and provide linear calibration of the capacitance signal from the ceramic sensing diaphragm. Benefits of using the pressure transducer over a normal type pressure switch is that the transducer is constantly monitoring pressures and sending signals to the engine control module (ECM), unlike the normal type pressure switch that has an upper and lower cut out point. The ECM will disengage the A/C compressor at low or high refrigerant pressures and electronic diagnostic equipment can be used to extract system pressure information making it easier when diagnosing problems.
High Side Charge Port
Pressure Transducer
Signal Electronics
Ceramic Diaphragm
Pressure Transducer
Air Conditioning Training Manual
Pressure Port
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INDEX
Components Protection Devices Engine Control Module (ECM) Body Control Module (BCM) Power Train Module (PCM)
- active and deactive the condenser fan; - increase engine idle speed when A/C system is activated; - deactivate the A/C compressor at high engine RPM; - delay A/C compressor engagement at engine cranking; - activate electrical engine fan at predetermined coolant temperatures - deactivate the A/C compressor when coolant temperature excessive; - deactive the A/C compressor at wide open throttle (WOT)
Micro processors (ECM, BCM or PCM) are used to engage and disengage the A/C electrical circuits controlling the compressor and condenser fan. Numeric signals from various sensors relating to engine speed, road speed, coolant temperature, A/C switch activation, pressure switches, A/C thermostatic switch, throttle position and kickdown are constantly being monitored by the ECM, BCM or PCM. These numeric signals are converted in the micro processors to calculations required to : - deactivate the A/C compressor at high/low system pressures; - deactive the A/C compressor at kickdown; Power Fuse Thermostatic Switch
PCM
High Pressure Switch B8
Blower Switch
A/C Switch
Low Pressure Switch
Compressor Clutch Field Coil
A/C Relay C2
Diode A/C Relay Energised only if the ECM provides the Earth
Thermal Protector
Fuse
Engine Cooling Fan Relay High Speed
A/C Pressure Switch F6
Fan Fusible Link
Two Speed Engine Cooling Fan BCM
Engine Cooling Fan Relay Low Speed
Air Conditioning Training Manual
Engine Cooling Fan Relay High Speed Control Engine Cooling Fan Relay Low Speed Control
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INDEX
Components Protection Devices Relays Relays are normally used in the A/C electrical circuit to protect switches that have a low current carrying capacity (ie a small contact area/weak pressure contact point) or for current draw differences between components. Shown below is an example of the difference in a circuit with and without a relay. Without Relay
A/C Switch
Battery 12 Volts
Voltage drop across A/C Switch approx 2 Volts
10 Volts
Compressor Clutch
Earth
Earth
With Relay
A/C Switch
Battery 12 Volts
A/C Switch Energises Relay
Relay
Compressor Clutch
12 Volts Earth Earth
Air Conditioning Training Manual
Earth
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INDEX
Components Sensors Sunload
Sunload Sensor
The sunload sensor is a photo chemical diode (PCD) located on top of the dashboard. This sensor sends a signal to the electrical climate control module (ECCM) indicating the strength of the sunlight (sunload) which influences the vehicle interior temperature.
34 5 2 1 0
100
0
6 7 8
200
If the sunload is high as signalled by the sunload sensor the ECCM will activate the highest blower fan speed and maximum cooling to compensate for this additional radiated heat load. Likewise, if the sunload is low (cloud cover) as sensed by the sunload sensor, the ECCM will reduce the blower fan speed and the system will not operate at maximum cooling. Ambient Temperature Sensor The ambient temperature sensor is a negative coefficient resistor (NTC) with a low voltage input. The sensor alters resistance depending on the ambient air temperature surrounding it. The sensor is located in the ambient air stream normally behind the bumper bar or front grille area. This sensor is used to monitor the outside temperature and is interconnected to a visual display in the instrument panel.
Ambient Temperature Sensor
Air Conditioning Training Manual
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Components Temperature Control Air Mix Door Temperature control is carried out by operating the temperature mode control, normally cable operated and connected to a door housed in the heater case. This door is located above the heater core and in the full cold position, completely covers the heater core. As more heat is required, the door is operated and moves away from the
heater core and allows radiant heat to rise and mix with the fresh or A/C air to increase the vent temperatures to the desired comfort level required.
Air Flow during Maximum Hot
Air Flow during Maximum Cold
Air Mix Door
Heater Core
Air Mix Door
Heater Core
Heater Control The heater tap is normally vacuum operated and has engine vacuum applied to it in the full cold position. This stops the flow of coolant to the heater core by keeping the heater tap closed.
Once heating has been selected, the vacuum is exhausted from the vacuum circuit via a vacuum switch, to the heater tap and the hot coolant then flows through to the heater core.
Vacuum Switch
To Mode Control
Air Conditioning Training Manual
Actuating Lever connected to the Temperature Control via a Rod
Plunger
From Vacuum Source
Heater Tap Vacuum Actuator
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INDEX
Components Mode Controls Vacuum Actuators -Single & Duel Stage The various air distribution duct doors located in the heater-A/C case are open and closed using a vacuum actuator.
➞
The vacuum actuator consists of a plastic or metal container housing a spring, rubber diaphragm and a connecting rod. Once vacuum is applied, the rubber diaphragm is pulled back bringing with it the connecting rod which is connected via a lever to an air distribution door and compressing the spring. When the vacuum is removed, the spring pushes the diaphragm and connecting rod back to the original position.
➞
Single Stage
Vacuum Released
➞ Vacuum Applied
Duel Stage
Vacuum Port 1st Stage Housing Vacuum Port 2nd Stage
Spring
,,,, ,, ,,, Spring
1st Stage Diaphragm
2nd Stage 1st Stage (Half) Fully Extended
Actuation Rod
2nd Stage Diaphragm
Vacuum Circuit Vacuum is directed to the desired distribution duct vacuum actuator, from engine intake manifold vacuum. A vacuum switch attached to the mode control knob redirects vacuum to the desired vacuum actuator.
Mode Direction Control
Mode Vacuum Control
Vacuum Actuators
Air Conditioning Training Manual
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INDEX
Components Mode Controls Air Mix Motors The air mix motor is actually a potentiometer balance resistor (PBR). It comprises of a small electrical motor, gears of varying sizes, a drive shaft and a printed circuit board. It is attached by means of a drive shaft to the air mix or temperature mode door main shaft. This motor regulates the temperature by moving the door closer to (cooler) or further from (hotter) the heater core. Variable low voltage signals are sent from the electronic climate control module (ECC) to move the air mix motor - which in turn moves the temperature mode door, to a predetermined position to regulate the vehicle interior temperature. The air mix motor position signals are also sent back to the ECC for reference as to where the air mix/mode door is positioned. Vacuum Solenoid Pack This method for operating the vacuum actuators is normally used in conjunction with the electronic climate control system (ECC). This type of climatic control is fully electronic. The vacuum actuators used for various air distribution modes are indirectly engaged and disengaged electronically via the vacuum solenoid pack
Actuator
The solenoid pack consists of a group of electrically activated vacuum solenoid valves using a common printed circuit board while enclosed in a single housing. Each solenoid is allotted to a vacuum actuator or vacuum valve (heater valve). Once the vacuum solenoid is energised by the ECC, an engine supplied vacuum can then flow through the solenoid valve to the relevant vacuum actuator to operate a mode. Likewise, once the vacuum solenoid is de-energised it then vents the vacuum from the line and actuator into the atmosphere.
Air Conditioning Training Manual
Vacuum Solenoid Pack
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INDEX
Components Electronic Temperature Control (ECC) ECC systems operate with the same basic components as in the manually controlled systems, such as the condenser, compressor, evaporator and heater. The major difference being that the ECC system can maintain a preset level of cooling or heating selected by the vehicles operator once the automatic mode is selected.
This is accomplished by adjusting: ● Blower fan speeds ● Air mode positions ● A/C activation
Electronic sensoring devices allow the ECC to respond to various changes in sunload, interior cabin temperature and ambient temperature. The ECC system will adjust automatically to any temperature and climatic changes, to keep the vehicle cabin interior within the pre-selected temperature range.
In Car Temperature Sensor
● Air mix door movement ● Flesh/Recirc door position
Control Display
AMB
Sunload Sensor
● Heater tap activation
-88.8
Air Mix Door Motor
Vacuum Solenoid Pack
C
AMUATNOU A L A/C
A 123
CLIMATE CONTROL
0FF
AUTO
MANUAL MODE
A/C
AMB
Compressor
Ambient Temperature Sensor
Evaporator Temperature Sensor
Air Conditioning Training Manual
Water Temperature Sensor
Blower Speed Resistor
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INDEX
Components Electronic Temperature Control (ECC) Whilst the systems main benefits are attained on the AUTOMATIC mode, the option for manual overide exists. But once manual mode has been selected by pushing the fan speed, A/C or mode switch, it takes away a function normally controlled by the processor in the ECC module making the processor adjust an alternative component to attain the pre-selected temperature.
An additional benefit of the ECC system is a self diagnostic function which when used will greatly reduce the time spent locating system faults.
Component Interface
IGN
Batt +
Power Source Circuit
IGN
5V
Blower Motor
5V
Blower Control
Reset Fail Safe Circuit
GND
Blower Control
In Car Sun 5V Air Mix Motor
Air Mix Door Output Operation Circuit
Intake
Central Processing Unit
Water
Input Interface Circuit
Ambient
Analogue to Digital Converter
Sensor
Evaporator
Mode
Vent
Mode
Defrost
IGN
Foot
Mode
Sensor
Water Temp.
Relay
ECM
A/C Request
IGN Comp.
Input Interface Circuit
Relay LCD Driver
Light
High Blower Speed Request
LCD Illumination Key Pad
Air Conditioning Training Manual
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INDEX
Retrofitting From Refrigerant R12 to R134a Introduction With the accelerated phase out of R12 ( 1 st January 1996 ) many compromises have to be considered and quite possibly accepted in retrofitting R12 automotive A/C systems to operate on an alternative refrigerant such as R134a. No direct “drop in” replacement refrigerant for R12 systems is available, even alternatives such as ternary blends require the replacement of components such as hoses, ‘O’ rings, filter drier's or accumulators. System lubrication, Air International and the majority of automotive manufacturers are recommending PAG (Poly Alkaline Glycol ) oil as the only oil replacement when retrofitting R12 automotive A/C systems to operate on R134a refrigerant. It is also recommended that if an R12 A/C system is functioning correctly and no refrigerant leaks are present DO NOT retrofit until absolutely necessary i.e.
-
What A/C repairs were last carried out and when?
-
What parts were replaced?
-
Is the A/C system already operating on an alternative refrigerant?
-
Is the A/C functioning/operating okay presently, if not, ask the owner for any known history of problems?
-
How long do they intend keeping the vehicle? This could alter the depth of retrofit? Do you replace the condenser with a more efficient design? Explain associated costs to the owner.
-
What warranty will be offered on the retrofit?
-
Any defects and leaks will have to be repaired before the R134a retrofit can take place. These costs will be over and above the retrofit price.
- Replacing a major component such as the compressor or condenser. - When R12 is no longer available. - Accident damage. Cost will be a very important issue if an R134a retrofit is to be undertaken, BUT do not sacrifice performance and reliability for the sake of cost. As further documented there will be temperature and pressure increases within the system. This will all depend on how the A/C system originally performed on R12, if the performance was marginal on R12 a retrofit to R134a WILL NOT improve that performance. Retrofitting the A/C system is probably the simplest part, the most important part prior to retrofitting will be the time spent talking to the owner discussing:
Air Conditioning Training Manual
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Retrofitting
INDEX
From Refrigerant R12 to R134a 1/ Initial Inspection - A full visual inspection of all components, hoses, signs of leakage, corrosion - also look for warning labels indicating what refrigerant is in the A/C system, an alternative refrigerant could already have been used. (NOTIFY THE OWNER OF EXTRA PARTS REPLACEMENT ABOVE RETROFIT COST REQUIRED TO BRING THE A/C SYSTEM BACK TO A FULLY OPERATIONAL CONDITION). 2/ Performance Check - Start engine, engage A/C, operate for 10 minutes at 1500 rpm, on max cooling and highest fan speed, insert thermometer probe into the centre vent and connect R12 pressure gauges. If required add sufficient R12 refrigerant (if available) to bring the A/C system pressures and centre vent temperatures to the manufacturers specifications. Take note of the pressure and temperature readings. (NOTE: RUNNING THE A/C SYSTEM FOR 10 MINS ETC. WILL ENSURE THAT MOST OF THE MINERAL OIL WILL BE TRAPPED IN THE COMPRESSOR). Check condenser airflow for restrictions. obstructions, such as insect screens, grass seeds and insect build up over the condenser face, also for any signs of system overheat. 3/ Leak Checking - Carry out complete leak check (To SAE J1628) using a dedicated R12 leak detection device. (To SAE J1627) (NOTIFY OWNER OF EXTRA PARTS NEEDED TO BE REPLACED ABOVE RETROFIT COSTS.) 4/ R12 Recovery- Recover refrigerant from the A/C system using a dedicated R12 recovery device (To SAE J1990). 5/ R12 Parts Replacements - Remove the components to be replaced as part of the retrofit to R134a, as recommended by the A/C system or vehicle manufacturers guidelines.
Air Conditioning Training Manual
THE MINIMUM - Filter drier or accumulator; - High side system ‘o’ rings through to the evaporator inlet; - Remove compressor and drain off mineral oil, add PAG oil. (To SAE J1660); - Fit high/low side R134a charging port adaptors (use a thread lock to secure to R12 charging port); - Retrofit warning labels. 6/ Flushing Option - If when removing components contamination is found ie. aluminium particles, it would be advisable to flush the system. Components such as the compressor, filter drier/accumulator and ‘o’ rings are to be replaced. Flush all remaining components with liquid R12 (if available) collected through a recovery device. Fittings will have to be manufactured for this function. 7/ Evacuation - Using R134a equipment, evacuate the A/C system for a minimum of 40 minutes at a vacuum of - 100kPa. 8/ Charging - Charge the A/C system with R134a to approx. 90% of the original R12 charge quantity eg. original R12 1000 grams, R134a retrofit charge 900 grams. 9/ Warning/Identification Labels - Remove all labels from the vehicle referring to the REPLACED refrigerant. Affix new R134a warning and oil/change quantity labels (to SAE J1660) to a prominent location in the engine bay. Write on labels all fitment information required in ballpoint pen. 10/ Performance Check - Take pressure and centre vent temperature readings, compare to the ‘baseline’ information taken in step 2. Remembering that R134a pressures will be 10 - 20% higher and centre vent temperatures possibly slightly higher also.
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Retrofitting
11/ Road Test - Carry out road test, again check performance in the various fan speeds and mode positions. Ensure if in an extended idle situation the compressor does not fast cycle on the high pressure switch (high pressure problem). If this occurs, especially in high ambient conditions, further work might be required, such as:
12/ Hand over - Explain to customer what exactly has been replaced, and any warranty implications.
● condenser (refer page 22); ● condenser fan (refer page 23); ● condenser seals (refer page 31); ● pressure switches with higher settings (refer page 41); ● removal of insect screens, etc. Filter Drier XH7 or XH9 Desiccant
Pressure Switch Higher Settings
CCOT System
R134a Adaptors
R134a Identification Label
Accumulator XH7 or XH9 Dessicant
Barrier Hose
CCOT System Condenser Fan
Air Conditioning Training Manual
Parallel Flow Condenser
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INDEX
Retrofitting Procedure PRE RETROFIT DISCUSSION WITH CUSTOMER
1 • • • •
Date of last repair to the A/C system. What parts were replaced, especially hoses. Is the system fully functioning. Has the A/C system been retrofitted with an alternative before. Costs could be incurred above the retrofit for non retrofit parts fitted. Explain that higher R134a pressures could cause slightly higher vent temperatures. What type of driving is mostly done, city, country, long high speed runs, etc.
• •
4
LEAK TEST
• •
• • • • •
•
•
• •
Damage. Cracked/burnt hoses. Oil leakage areas. Charge port fittings. Labels indicating a refrigerant other than R12 used. Noises such as compressor.
Connect pressure gauges. Run A/C system for a minimum of 10 minutes on :- highest blower speed, maximum A/C at 1500 RPM. Mark down pressure and temperature readings for comparison after the retrofit. If low refrigerant charge is confirmed, add required amount of R12 and re-test.
R12 R12
REFRIGERANT RECOVERY
5 •
PERFORMANCE CHECK
Recover the refrigerant R12 into an R12 specified recovery machine. If the accumulator or filter drier ices up on the lower section after recovery, liquid refrigerant is trapped. Lightly warm up the area with a hair drier and recover again.
• •
6
PARTS FOUND LEAKING IN STEP 4
•
Components found leaking in Step 4 have to be replaced using R134a specific components such as R134a nylon barrier hoses. Any components replaced other than components required for the R134a retrofit will be over and above the retrofit price — contact the owner for approval.
R12 R12 R12
Remove the compressor and drain all the mineral oil by turning the compressor upside down and rotating the front plate.
•
•
SYSTEM CONTAMINATION
8 •
Inspect the interior of the discharge hose for signs of contamination such as aluminium flakes. If contamination is found flush individual components, tubes and hoses with liquid R12 collected through an R12 recovery machine.
R12 R12
IMPORTANT
•
•
Using an electronic R12 leak detector thoroughly check all components, fittings etc. for refrigerant leaks. Always check under components and fittings for refrigerant leaks as R12 is heavier than air.
MINERAL OIL REMOVAL
7
3
VISUAL
R12
•
A/C SYSTEM INSPECTION
2
Refill the compressor using the recommended manufacturers PAG oil only. Adding PAG oil:- Fill the compressor through the suction port while turning the front plate. Fill to the same oil quantity as specified for the original R12 fill.
•
Air Conditioning Training Manual
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INDEX
Retrofitting Procedure
9
RETROFIT COMPONENT CHANGES (THE MINIMUM)
•
10
Change all O-Rings in the engine bay high and low sides to HNBR (R134a) type (green), including compressor. Filter drier or accumulator suitable for R134a XH7 or XH9 desiccant. R134a charging port adaptors secure with threadlock. R134a warning and installation labels. Remove any labels referring to R12. If any A/C hoses (non barrier type) have been replaced in the last 3 months, it is recommended they be replaced again with barrier type hose.
RETROFIT PARTS REPLACEMENT CONSIDERATIONS
11
EVACUATION
•
(This can be clarified once Step 13 completed) Larger condenser with improved heat rejection. Condenser fan. High pressure switch with higher compressor cut-off setting. Orifice tube with smaller I.D. Foam seals between condenser and radiator to stop engine reheat air and ambient air bypass.
Using an R134a deep vacuum pump evacuate the R134a retrofitted system for a minimum of 30 - 45 minutes, to a vacuum of minus 100 kPA (29.8 in hg). Carry out a vacuum holding test to ensure no major leaks are evident.
R134a R134a R134a
• • • •
• • • • •
•
FURTHER RETROFITTING REQUIRED
12
CHARGING
• • • •
PERFORMANCE TESTING AND ROAD TEST
13 •
Using an R134a charging station refill the A/C system to 90% of the original R12 refrigerant charge. Example:R12 = 1000grams 90% — R134a = 900grams Disregard the filter drier sight glass (if fitted) as this could provide a false indication (PAG oil foaming). Carry out complete leak check using an R134a electronic leak detector. Check under fittings and components.
HAND OVER TO CUSTOMER
14
Carry out pressure and centre vent temperature check. Compare these figures to the ones taken in Step 3. Road test vehicle at various road speeds and fan positions . Return to an idle situation, stay at idle for 20 minutes, if possible, to check effect on pressures and centre vent temperatures. If the pressures and temperatures are above what is deemed acceptable compared with Step 3, contact owner and suggest alternatives such as in Step 10.
•
Explain to customer exactly what has been replaced. Show the R134a warning labels and charging ports, now indicating only R134a and PAG oil can be used in the system. Re-affirm that a slight drop off in performance could be experienced compared with pre-retrofit. Outline warranty coverage.
R134a R134a R134a •
•
• • •
R134a SAFETY AND PRECAUTIONS SAFETY
• • • •
Do not inhale R134a and PAG oil. Do not allow PAG oil to contact bare skin. Work in a well ventilated area. Always wear gloves and glasses.
R134a
PRECAUTIONS
• • • •
Keep PAG oil containers tightly capped as PAG is highly hygroscopic. Do not overcharge the system. Do not rely on the filter drier sightglass when charging. Ensure there is no air in the A/C system. Excessive air can make R134a combustible. Do not allow PAG oil to contact vehicle paint work.
Air Conditioning Training Manual
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INDEX
Equipment Charging Stations These are two methods of charging refrigerant into Dial-a-Charge (by volume) an A/C system. They are: By volume - using a graduated charging dial cylinder. By weight - using electronic scales with LCD read out.
Manifold Gauge Set
Graduated Cylinder
Both methods work well, but because R134a is charge sensitive and most A/C system filter drier's have no sight glass. It is recommended to Vacuum charge the system to the manufactures Pump specification using electronic weighing scales. The advantage of using electronic scales over a dial -a - charge type is that most dial - a- charge Strain Gauge (by volume) cylinders only hold 4400 grams max. (before being refilled) which is enough for approximately five (5) Manifold Gauge Set A/C system charges. The electronic scale type uses a refrigerant cylinder of up to 25 kilograms enabling 25 A/C system charges to take place before changing over the cylinder.
Electronic Scale Type Charge/Evacuation Station
Display Refrigerant Cylinder
Strain Gauge Scales
Vacuum Pump
The charging cylinder sits on a set of scientific quality scales and as the refrigerant is metered into Recovery/Recycle Unit the A/C system the weight of the charging cylinder is reduced. This reduction reads out on an LCD display panel. Caution:As these stations use scientific grade scales, care must be taken placing cylinders on the scales and also moving them around in R134a the workshop.
Air Conditioning Training Manual
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INDEX
Equipment Combination Units Rather than have a unit that only charges and evacuates an A/C system, there are combination units that carry out all the necessary servicing functions. Operations are entered into an electronic key pad. These include : ●
Charging to the specified amount.
●
Evacuating for any duration required
●
Recovering the refrigerant
●
Recycling the refrigerant
●
Injecting the lubricant
All these functions can be programmed into the unit via a control panel. The unit will automatically carry out all the pre-selected operations. Low Side Hand Valve High Side Hand Valve
Pressure Display Weight/Time Display
Buttons for different functions: ● ● ● ● ●
Charging; Recovery; Recycle; Evacuation; Oil Inject.
R134a
Air Conditioning Training Manual
Page 71
INDEX
Equipment Gauges With the introduction of R134a, most equipment manufactures have changed gauge faces to read in either:
■ R12 was mostly in pound per square inch. (P.S.I.)
● BAR pressure units; ● KILOPASCALS ( kPa ); ● KILOGRAM CENTIMETRE SQUARE (KG/CM2); ● 1 BAR = 100 kPa; ● 1 KG/CM2 = APPROX 100 kPa; R134a Gauge
R12 Gauge Hose 400
300
3
200
4
LOW
2
1500
6 7
0 0
1 -100
15
1000
5
1
100
2000
10
600
700
500
20
HIGH
5
2500
25 30
8
BAR KPa
Rubber
500
3000
35 800
0
BAR KPa
3500
Rubber Reinforcement
ACME Thread (Female)
Rubber Nylon
ACME Thread (Male)
Reinforcement
Air Conditioning Training Manual
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INDEX
Equipment Recovery & Recycling R134a is a non ozone depleting refrigerant but from a cost point of view and the fact that R134a adds slightly to the green house effect, it is still advisable that it be recovered and recycled. Due to the fact that most R134a A/C systems have no sight glass in the FDR, you may be required to remove the refrigerant more often and charge to the specified amount.
R134a Charge Adaptor (High Side)
R134a Charge Adaptor (Low Side)
R134a
IMPORTANT NOTES ● ● ●
Use only a specified R134a Recovery or Recovery/Recycle machine for R134a refrigerant. Change device filters when suggested by equipment manufacturer. Ensure oil collected during recovery is replaced into the A/C system ( clean oil ).
Air Conditioning Training Manual
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INDEX
Equipment Vacuum Pump Owing to the highly hydroscopic nature of the R134a lubricating oil (PAG), it is essential that a deep full vacuum is reached.
Low Side Gauge
tive Pressur i s e Po
The vacuum pump must pull: -100 kPa ( - 1 BAR or - 1 KG/CM2(14.7psi) )
400
300
3
200
500
4
LOW
2
5 6
1
100
7 0
0
1
g Ne re P
-100
600
700
8
BAR kPa
800
s s a ti v e ure
Servicing the Vacuum Pump
Vacuum Pump
Before commencing the evacuation, check the oil level sight glass located on the vacuum pump. Refer to manufactures specifications for the correct oil level. After approximately 17 evacuations, drain all the oil from the vacuum pump and replenish with new vacuum pump oil. Oil changing is required due to the hygroscopic nature of vacuum pump oil. Pulling the A/C system into a vacuum boils off any moisture which in turn contaminates the vacuum pump oil.
Caution ●
Ensure only the recommended lubricating oil is used. This is normally of 3GS Viscosity.
Air Conditioning Training Manual
Breathe Cap Ensure Oil Breathing Hole Clear Oil Level Use 3GS Vacuum Pump Oil
Drain Plug Connection to Manifold Set Centre (Yellow Hose)
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INDEX
Servicing Refrigerant Safety As R134a has a very low boiling point, care must be taken when it is being handled. The following safety precautions must be followed:
Eye Protection
● Always wear eye protection; ● Wear gloves; ● Don’t allow R134a to contact bare skin. (as this causes frost bite);
Hand/Skin Protection
● Do not heat containers of R134a; ● Provide adequate ventilation when charging or recovering R134a, as it is heavier than air; ● Use care when hot water steam cleaning the engine. Hot water on the air conditioning pipes and tubes could create thermal expansion of the refrigerant contained in the system;
Do Not Heat Containers
● Avoid breathing R134a vapour; ● Do not transfer refrigerant from cylinder to cylinder using a pump without knowing when then bottle being filled has reached 80 % of its capacity, as the remaining 20 % is used for thermal expansion.
Do Not Apply Steam Cleaning Directly
Air Conditioning Training Manual
Do Not Transfer Refrigerant
Avoid Breathing Refrigerant
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INDEX
Servicing Leak Detection Refrigerant leaks must be found and rectified, as a low refrigerant charge will cause system damage;
Leak Detection Methods Visual Leak Detection
● Air and moisture can enter a system at the leak point and cause internal components to corrode. ● Compressor lubrication depends on refrigerant circulation.
When a refrigerant leak occurs, it is common for the lubricating oil to escape along with the refrigerant. The presence of oil and encrusted dust around hose fittings, joints and components will indicate a leakage point.
● Refrigerant helps cool the compressor.
Pressure Relief Valve or Fusible Pin
Joints
Front Seal
Joints
Joints
Pressure Relief Valve
IMPORTANT NOTES ● ●
Wipe dirt etc. from the areas being inspected; This also applies for all types of leak detecting.
Air Conditioning Training Manual
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INDEX
Servicing Leak Detection & Detectors Soap Solution A mixture of dish washing liquid and water applied around the A/C system pipes and fittings will form bubbles at the leakage points.
Electronic Leak Detector These leak detectors operate in various ways, the most common being that when the unit is turned on, a low ticking sound can be heard and once the probe locates a leak, the ticking sound increases to a high pitched noise. This can be achieved by moving the sensing tip slowly around the underside of components and fittings at a distance of approximately 5mm. DO NOT allow the sensing tip to contact components or fittings as false readings and tip damage will occur.
5mm
IMPORTANT NOTES ● ● ● ● ● ● ●
Only use a detector designed to sense the refrigerant in the A/C system you are testing; Always clean dirt and grime from the section you are testing otherwise the sensing tip will be clogged; Regularly check the detectors sensitivity by sampling a small leak of refrigerant from a charging port shrader valve; Never allow the tip to contact the component being checked; Always check under fittings or components as refrigerant is heavier than air; Check for refrigerant leaks out of the wind; Check for refrigerant leaks with engine stopped.
Air Conditioning Training Manual
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INDEX
Servicing Leak Detection & Detectors Ultraviolet Fluorescent System A fluorescent coloured dye is injected into the A/C system and allowed to circulate, then a specially designed ultraviolet lamp is passed over each component in the A/C system. If a leak is evident, the coloured dye glows bright. This method is exceptionally good for pin pointing a small leak.
IMPORTANT NOTES ●
Use the recommended dye for the refrigerant used in the A/C system;
●
The only fluorescent dye recommended by ‘Sanden’ is the ‘Iglo’ brand;
●
Always check manufactures recommendations, prior to using this method.
Refrigerant Dye Normally red in colour, this dye is injected into the A/C system via the charging port. The A/C system is then operated, if a leak is present, this red dye will emerge and show as a stain around the fitting or component. This method is also good for pin pointing a small leak but leaves a heavy residue in the A/C system
Dye Injector
It is advisable to ask the customer to return in approximately one weeks time as the dye could take longer to emerge if the A/C system has a small leak.
IMPORTANT NOTES ●
Check with the A/C system manufacturer to see if these dyes are suitable, and will not damage the A/C system components, such as the filter drier receiver (FDR) desiccant. Failure to do so could void the manufactures warranty.
●
Always check manufacturers recommendations, prior to using this methods.
Air Conditioning Training Manual
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INDEX
Servicing Lubrication Component Replacement
Receiver Drier
When replacing components, check the manufacturers recommendations on the quantity of oil to be added to the new component before installation. This is normally found in the particular vehicles workshop manual. EXAMPLES of approximate quantities: Compressor ● Evaporator
-
40cc
● Filter drier
-
25cc
● Condenser
-
30cc
● Accumulator
-
40cc
● Evaporator
-
40cc
● Hose blown ● Tubes
-
Hoses
50cc 20 cc
Compressor (New Replacement) Drain and measure the lubricating oil from removed compressor. Likewise, remove the oil from the new compressor, refill this new compressor with the same quantity of oil drained from the old compressor. Use the new clean oil removed from the new compressor plus 10cc to allow for any internal oil coverage.
Condenser
Removed Compressor Faulty Compressor
New Compressor 100 + 10cc = 110cc
E.G. 100cc Removed
Air Conditioning Training Manual
New Compressor
Page 79
INDEX
Servicing Lubricating Oil Oil Injector Lubricating oil can be added to a non opened A/C system by using an oil injector. Fill injector container to the required oil level. Pull the A/C system into a deep vacuum, attach the oil injector hose to the low side charging port, open the oil injector valve and allow the vacuum created in the A/C system to pull the lubricating oil into the low side of the A/C system. M CUU VA
IMPORTANT NOTES ●
Ensure only PAG oil is used with R134a refrigerant;
●
Min vacuum - 100kpa;
●
Use only specified PAG oil to suit the compressor..
Air Conditioning Training Manual
Page 80
Servicing Flushing a Contaminated System (as per SAE 1661 Standards) If a seized or damaged compressor is to be replaced, inspecting of the discharge hose interior is advised. On inspecting the interior of the discharge hose, if particles or slivers of aluminium are found, flushing of the A/C system is required including a new filter drier.
machine and can be used again. Component or tube connections (mostly self-made), will have to be used and flushing carried out with the refrigerant in liquid form ie. the decanting cylinder turned upside down (inverted).
We recommend flushing individual components or system sections with refrigerant R134a, this refrigerant should be collected via a recovering
INVERTED DECANTING CYLINDER (LIQUID)
FLUSH GUN FLUSH, THEN REVERSE FLUSH
RECOVERY DEVICE
SELF MADE FITTING CONDENSER
IMPORTANT NOTES ●
Failure to flush a contaminated system will lead to blockages in the condenser filter drier or TX valve, and possibly cause compressor damage.
Air Conditioning Training Manual
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INDEX
Servicing Preparation Before servicing or diagnosing an A/C system there are preliminary checks that should take place.
Damaged or Blocked Fins Engine not Overheating
These include : ●
Checking for visual hose damage and chaffing.
●
Ensure the condenser cooling fins are not blocked with obstructions such as insects, and the fins are straight.
●
Hoses Damaged
Condenser fan operates and runs in correct direction;
●
Engine/radiator not over heating.
●
Inspect drive belts for correct tension and damage.
●
Engine viscous fan locks in at the correct temperature.
●
Compressor cycles on and off.
●
Evaporator drain hoses not blocked.
●
Heater turned off in the full cold mode position.
●
Air mix door fully closed.
●
A/C switch illuminates when activated.
●
No vacuum hose leakage.
●
Dash vents open and close fully.
●
No air leaks between evaporator case and heater case.
●
Blower fan has all speeds operational.
●
Any evidence of refrigerant leakage and oil staining at components or connections.
Air Conditioning Training Manual
Damaged or Blocked Fittings
Drain Hose Blocked Correct Belt Tension
Dash Vents Fully Open Fan Speed on High
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INDEX
Servicing Pressure Gauges Introduction An accurate diagnosis and determination of air conditioning system function and, more importantly, malfunction, depend largely upon the ability of the technician to interpret gauge pressure reading. The importance of a refrigeration technicians manifold and gauge set is often compared to that of a physician’s stethoscope. An improper gauge reading will relate to a specific problem. More than one problem may be associated with a particular gauge reading, however. A system operating normally will have a low-side gauge pressure reading that corresponds with the temperature of the liquid refrigerant as it becomes a vapour while removing heat from the air flowing over the evaporator coil surface. The high-side gauge readings should correspond with the temperature of the refrigerant vapour as it becomes a liquid while giving up its heat to the ambient air flowing through the condenser. Any deviation from ambient dependant normal gauge readings, other than slight, indicates a malfunction. This malfunction, if within the system, may be caused by a faulty control device, a restriction, or a defective component. It should be noted that improper mounting or location of components in a newly installed system may affect system performance. The vehicles engine may also affect system performance and will be noted as abnormal gauge readings.
Adjusting Screws
3
200
Pressure Gauge Pre Check
400
300
4
LOW
2
Air Conditioning Training Manual
6 7
0
1 -100
2000
15
1000
5
1
100
0
Always inspect pressure gauges to ensure the needles rest as zero on both low and high sides, if the needles(s) do not rest on zero, remove the hoses, open both taps, detach the dial face and gently turn the adjusting screw until the needle(s) rest on zero. Reconnect hoses and close taps.
1500 500
10
600
700
500
20
HIGH
5
30
8
BAR kPa
2500
25 3000
35 800
0
BAR kPa
3500
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INDEX
Servicing Evacuation & Charging Procedure Performance Testing (General) STEP 1. Park vehicle in a shaded area. Take note of ambient temperature. STEP 2. Open both front windows and engine hood. STEP 3. Connect both high and low pressure service hose coupling valves to the system filling ports. STEP 4. Open all dash louvers and adjust to the straight ahead position. STEP 5. Insert thermometer probe approximately 50mm into the centre vent louvre. STEP 6. Set the controls to: A. Fresh air position; B. Maximum cooling; C. A/C on; D Highest blower speed.
STEP 7. Start engine, bring engine speed to 1700 RPM then allow pressure gauge needles to stabilise. STEP 8. Take pressure and temperature readings. Compare these to the manufacturers performance charts found in appropriate workshop manuals. NOTE: Only take pressure and temperature readings when the compressor is engaged. As you can see from the above typical performance test, the A/C system is put under an increased load such as doors and engine hood open and high blower speed. If an A/C system can perform to the manufacturers specifications under these loads, in normal driving situations with engine hood, windows closed and possibly a lower blower speed, centre vent temperatures will be much lower.
R134a
Air Conditioning Training Manual
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INDEX
Servicing Performance Chart Example
Suction Pressure (kg/cm2)
Suction Pressure Vs Ambient Temperature 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0
RH:80%
RH:30%
15
17
19
21
23
25
27
29
31
33
35
Ambient Temperature (oC)
Example Ambient Temperature = Pressure = Centre Vent =
25° C 1.8KG/cm2 4°C
FACE AIR OUTLET TEMPERATURE (oC)
Suction Pressure Vs Ambient Temperature 22 20 18 16 14 12 10 8 RH:80%
6 4 2 0
RH:30%
15
17
19
21
23
25
27
29
31
33
35
Ambient Temperature (oC)
Air Conditioning Training Manual
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INDEX
Servicing
Thermistor & Amplifier Testing (Electronic Compressor Clutch Cycling Control) Thermistor Testing
Evaporator temperature 25°C. Thermistor resistance should be 2KΩ (2000 ohms)
KΩ
Resistance
1. Disconnect the thermistor electrical plug. 2. Measure the resistance between the two terminals in the thermistor electrical plug. 3. Consult the graph and compare the resistance value eg.
8 7 6 5 4 3 2 1 0 0 5 10 15 20 25 30 35 40
Temperature (Co)
Amplifier Testing All amplifiers are sealed electronic units and cannot be tested. The only testing that can be performed is power/signals going to and from the amplifier. A workshop manual with wiring diagrams is required for this testing.
Air Conditioning Training Manual
Amplifier
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INDEX
Servicing ECC (Electronic Climate Control) - Diagnostic Testing Example
PRESS
Components LCD and Display Circuits Readout in Test AMB OFF
+
AMB
ALL
Sub Stage Test
Buttons Lower Display
Blue Button
Main Display Display 1
Display 1
Red Button
Display 2
Display 1,2
All of the Screen Segements, Numerics and Icons Displayed
LCD
Sun Load Sensor
PBR Feedback Sensor
Air Mix Motor Supply
% 0 to 99
% 0 to 50
% 0 to 99
% 0 to 99
✘ = Sensor Open or Short Circuited
✔
Water Evaporator Intake In Car Ambient Test Sensor Temperature Temperature Temperature Temperature Temperature Sensor Sensor Sensor Sensor Sensor
AMB
Auto
Sensor Inputs
Large Display Range
✔
AMB
Manual
Fan and Step Speeds
AMB
AMB
Solenoids Relay and Circuit Operation
A/C
Air Mix Motor and PBR Feedback
Display A
Display 3 Display 1,3 Display 1,2,3
°C °C °C -30 to +55 -30 to +55 -30 to +55
✘
Operating
Demist
Fresh/Recirc
Foot
% 0 to 99
Face Vent
A/C Relay
Water Tap
Solenoid Relay State
Off
On
Off
On
Off
On
Off
On
Off
On
Off
On
Large Display
0
1
0
1
0
1
0
1
0
1
0
1
Speeds Large Display
= Sensor in Range Confirm Operation of Circuit i.e. Air Flow Water Flow Clutch Engagement
Red Button to Step up through Fan Speeds
0
1
2
3
4
5
6
7
8
9
10
12
13
Motor State
Motor Stationary
Motor Runs to Hot Position
Motor Runs to Cold Position
Confirm Motor Operation - Inspect for Gear Movement
Large Display
0 to 99
99
0
Requires Conversion to 0° to 60° Range for Air Mix Flap Position
Air Conditioning Training Manual
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INDEX
Servicing Diagnosis for A/C Systems Variable Stroke Harrison V5 Compressor
This test is designed for typical workshop conditions: ● ●
21 -37°C; Various Humidities and Sun Load.
Follow the chart exactly to create enough cooling load to cause the V5 compressor to operate at full stroke. Accurate results will not be achieved otherwise
Neutralise internal vehicle temperature to workshop ambient conditions, insert thermometer into centre duct.
● ● ● ●
Hood Up; ● Open doors/windows; Temperature lever at full cold; Normal A/C mode; ● Hi blower speed; Engine at fast idle (1500 rpm).
Condenser fan runs during all A/C modes.
Close doors/windows. Set A/C controls to: ● ● ● ●
Normal A/C Mode; High Blower Speed; Temperature lever at full cold; Normal A/C mode;
Condenser fan does not run in A/C modes.
Reference cooling fan diagnosis section of service instructions
Run engine at idle for five minutes.
Record: ●
●
High and low side pressures after A/C system has been operating for five minutes; Centre outlet duct temperature.
Air Conditioning Training Manual
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INDEX
Servicing Diagnosis for A/C Systems Variable Stroke Harrison V5 Compressor Diagnostic Chart 1.
Use the following chart which corresponds to the present ambient temperature.
2.
Read the high and low side pressure and note the letter coded area in which they intersect.
3.
Match the letter code with the corresponding code in the diagnostic chart. A. Normal system; B. Low refrigerant; C. Refrigerant overcharge or receiver/dryer restricted; D. TXV closed; E. TXV stuck open; F. Compressor not pumping.
Example Ambient
-
32°C;
Low Pressure
-
200 kPa;
High Pressure
-
1400 kPa;
= Grid A (Refrigerant system normal)
550 F 400 280
D
140
B
E C A 700
1400
2100
2700
Ambient 26.5°C LOW SIDE PRESSURE (kPA)
LOW SIDE PRESSURE (kPA)
Ambient 21°C 550 F 400 280
E
D
140
C B
A
700
1400
2100
HIGH SIDE PRESSURE (kPa)
HIGH SIDE PRESSURE (kPa)
F 400
EXAMPLE
E 280
C D A
140
B 700
1400
2100
2700
HIGH SIDE PRESSURE (kPa)
Air Conditioning Training Manual
Ambient 37.5°C LOW SIDE PRESSURE (kPA)
LOW SIDE PRESSURE (kPA)
Ambient 32°C 550
2700
550 F 400 280
D
140
B
E A
C
A 700
1400
2100
2700
HIGH SIDE PRESSURE (kPa)
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INDEX
Servicing TX Valve Diagnosis If when carrying out pressure gauge diagnosis it is found the TX valve is at fault, ie.
Opening Test
Jammed fully open - high/low pressure too high, OR Jammed fully closed - low pressure zero to a vacuum; then follow the testing procedure below. Testing a. Remove the evaporator case and dismantle; b. Detach the TX valve pressure compensating tube and temperature sensing bulb from the evaporator outlet side; Mark the area on the outlet tube where the sensing bulb is clamped when replacing a TX valve. This sensing bulb must be fitted in exactly the same position. Opening Test: warm the temperature sensing bulb by hand, the TX valve should now be fully open. This can be verified by blowing through the valve.
Closing Test
Closing Test: into a container of water and crushed ice, place the temperature sensing bulb and gently stir, the TX valve should now be fully closed. This can be verified by blowing through the valve. If any of the above tests fail, replace the TX valve with the correct type ie (tonnage and super heat). Ensure new ‘O’ rings are used and that the temperature bulb is in direct contact with the evaporator outlet tube and that the bulb is covered with insulating material to ensure no false temperature readings are obtained. Caution -
when bending the temperature sensing tube to fit, care must be taken not to break it as this tube is hollow and contains refrigerant.
Air Conditioning Training Manual
Water and Crushed Ice
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INDEX
Servicing Pressure Switch Electrical Test When tracing a fault in the A/C circuit, always check for power at both sides of possible pressure switch terminals with a multimeter. If the pressure switch is deactivated this could indicate a refrigerant over or under charge.
Thermostat A/C Switch High Pressure Switch
Low Pressure Switch
Medium Pressure Switch
Compressor Clutch
Air Conditioning Training Manual
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INDEX
Servicing Evacuation & Charging Procedure
ΣΠΕΧΙΦΙΕ∆ ΧΗΑΡΓΕ _ _ _ _+/−_ _ _ _ ΓΡΑΜΣ
NOTE: 1. Gloves and safety glasses must be warn. 2. Work in a well ventilated area. 3. Do not smoke near refrigerant. 4. Avoid PAG oil contacting paint work. Wash off immediately.
LOW
HIGH
Fig. 1
B
A C
D
E F G
H REFRIGERANT RECOVERY UNIT
STEP 1 EVACUATION
NOTE:
Start vacuum pump, open valve F, open valves A & C low pressure filling hose. High side gauge reads below zero
High side gauge not below zero
Blockage or leak evident in system. find cause and rectify.
Leave valves A, C, & F open. Slowly open high side valves B & D. Evacuate system to 6 kpa absolute. Close valves A, B & F. System must maintain 6 kpa -absolute for a minimum of 15 mins. Low pressure gauge needle steady Recover refrigerant from system, open valves A, B, C, D, E and H. After the recovery procedure close valve E. Open valve F and continue the evacuation procedure for a minimum of 15 mins then close valves A, B & F. Turn pump off. (Refer Fig. 1)
VACUUM PUMP
Indicates stop tap or valve-fit these whenever a hose has to be removed
STEP 2 LEAK TESTING Partially charge system with 200 grams of refrigerant through high filling hose.
Low pressure gauge needle rises.
Locate leakage using an electrical leak detector. Check on the underside of all fittings and components
Continue evacuation for 15 mins.
Recover refrigerant from system open valves A, B, C, D, E, & H. (Refer Fig. 1)
Partially charge system with 200 grams of refrigerant Check for leakage using an electronic leak detector
Air Conditioning Training Manual
Repair leak source Continue with evacuation and charging procedure as per steps 1-3
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INDEX
Servicing Evacuation & Charging Procedure STEP 3 CHARGING SYSTEM
LOW
HIGH
B
A
Warning: Never run compressor without refrigerant in system as the compressor relies on refrigerant/oil flow. Any oil displaced during the refrigerant recovery process must be replaced in the system before charging can commence. The R134a system uses P.A.G. (polyalkylen glycol) lubricating oil. Use specified oil type.
C
D
E F G
H REFRIGERANT RECOVERY UNIT
Warning: Never charge system through the high side with the compressor running.
VACUUM PUMP
Fig. 2
Open high side valves B, D & G. Without exceeding the specified amount, allow as much refrigerant as possible to enter system Close valves B & D. rotate compressor front plate 12 revolutions to ensure no liquid is trapped in the compressor.
LOW
Start engine set to fast idle. Activate A/C switch. Set controls to maximum cooling and high fan speed.
HIGH
B
A C
Open low side valves, A & C slowly and complete the charging process (If required). Caution: do not allow more than 275 kpa to register on the low side gauge during charging.
Fig. 3
H D REFRIGERANT RECOVERY UNIT
First Aid: In the event of R134a contacting the eye, carry out the folllowing procedure:-
Close all valves and taps. Remove high and low filling hoses, make sure valves C & D are closed. Connect high side filling hose to recovery unit inlet side. Open valves A, B & D. Switch on recovery machine and remove all refrigerant in filling hoses. (Refer Fig. 3) Carry out performance testing. Refer appropriate workshop manual for specifications.
1. Do not rub eye 2. Splash large quantities of water into the eye to raise the temperature. 3. Continue to irrigate the eye for 15-20 mins. 4. Take patient without delay to hospital or physician. 5. Do not attempt to treat yourself.
Air Conditioning Training Manual
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INDEX
Servicing ΠΡΟΒΛΕΜ 400
300
3
200
4
LOW
2
1500
0
15
1000
5 6 7
0
2000
500
1
100
ΧΟΝ∆ΙΤΙΟΝ
10
600
700
20
HIGH
25
5
500
30
8
1
3000
35
BAR KPa
-100
2500
BAR KPa
0
800
3500
Εξχεσσιϖε αιρ (Νον Χονδενσαβλεσ) (ΧΧΤΞς/ΧΧΟΤ Σψστεµ)
400
300
3
200
4
LOW
2
1500
5 6 7
0
0
1 -100
15
1000
1
100
2000
500
10
600
700
20
2500
HIGH
25
5
500
30
8
3000
35
BAR KPa
800
BAR KPa
0
3500
Λοω Σιδε Γαυγε − Ηιγη; Ηιγη Σιδε Γαυγε − Ηιγη; ∆ισχηαργε Αιρ − Σλιγητλψ Χοολ; Νοτε − Λοω Σιδε Πρεσσυρε Γαυγε νεεδλε δοεσ νοτ φλυχτυατε ωηεν χοµπρεσσορ χψχλεσ Ον ανδ Οφφ.
ΧΑΥΣΕ ● Λαργε αµουντσ οφ αιρ ανδ µοιστυρε ιν σψστεµ χαυσεδ βψ ινσυφφιχιεντ εϖαχυατιον τιµε ορ νο εϖαχυατιον αφτερ ρεπαιρινγ ορ σερϖιχινγ τηε σψστεµ; ● Λεακινγ χοµπονεντσ ωιτηιν τηε σψστεµ αλλοωινγ µοιστυρε ανδ αιρ το εντερ.
Λοω Σιδε Γαυγε − Ηιγη; Ηιγη Σιδε Γαυγε − Λοω; Χοµπρεσσορ − Νοισψ; ∆ισχηαργε Αιρ − Ωαρµ; ∆ισχηαργε Ηοσε − Χοολ.
● Χοµπρεσσορ φαυλτψ, ιντερναλ φαιλυρε; ● Βλοχκαγε ιν συχτιον ηοσε αφτερ τηε λοω σιδε φιλλινγ πορτ; ● ΧΧΟΤ σψστεµ − βλοχκεδ αχχυµυλατορ.
Λοω Σιδε Γαυγε − Ηιγηερ ορ λοωερ τηαν χοντρολ ποιντ πρεσσυρε; Ηιγη Σιδε Γαυγε − Νορµαλ; ∆ισχηαργε Αιρ − Χοολ ονλψ ιφ αβοϖε χοντρολ ποιντ; Εϖαπορατορ − Φρεεζεσ υπ ιφ τοο φαρ βελοω χοντρολ ποιντ; Νοτε − Ρεφερ το αππροπριατε ωορκσηοπ µανυαλ φορ λοω σιδε χοντρολ ποιντ πρεσσυρε.
● Χοµπρεσσορ χοντρολ ϖαλϖε φαυλτψ ορ ινχορρεχτ ϖαλϖε ρατινγ υσεδ. Τηεσε ϖαλϖεσ αρε σταµπεδ ωιτη α λεττερ χοδε ον τηε ϖαλϖε βοδψ ινδιχατινγ τηε πρεσσυρε χοντρολ ποιντ φορ τηε λοω σιδε οφ τηε σψστεµ. εγ. Χοδε Ψ∏ Ψ=290κΠΑ (αβσολυτε) = 160−200κΠΑ. (Λοω γαυγε ρεαδινγ) Νοτε − Ρεφερ αππροπριατε ωορκσηοπ µανυαλ.
Χοµπρεσσορ Μαλφυνχτιον (ΧΧΤΞς/ΧΧΟΤ Σψστεµ)
400
300
3
200
4
LOW
2
1500
0
7 0 1 -100
15
1000
6
1
100
2000
500
5
10
600
700
500
20
HIGH
5
25 30
8
BAR KPa
2500
3000
35 800
0
BAR KPa
3500
Χοµπρεσσορ Χοντρολ ςαλϖε Μαλφυνχτιον (Ηαρρισον ς5 ςαριαβλε Στροκε Χοµπρεσσορ)
Air Conditioning Training Manual
Page 94
INDEX
Servicing ΠΡΟΒΛΕΜ 400
300
3
200
4
LOW
2
1500
15
1000
6 7
0
0
2000
500
5
1
100
ΧΟΝ∆ΙΤΙΟΝ
700
30
3000
35
BAR KPa
-100
25
5
500
8
1
2500
HIGH
10
600
20
800
BAR KPa
0
3500
ΧΑΥΣΕ
Λοω Σιδε Γαυγε − Λοω το ςαχυυµ; Ηιγη Σιδε Γαυγε − Λοω; ∆ισχηαργε Αιρ − Σλιγητλψ Χοολ; Οριφιχε Τυβε − Φροστ βυιλδ υπ; Λοω Πρεσσυρε Σωιτχη − ∆εαχτιϖατεδ.
● Οριφιχε τυβε φιλτερ σχρεεν βλοχκεδ ωιτη δεβρισ συχη ασ αλυµινιυµ παρτιχλεσ.
Λοω Σιδε Γαυγε − Ηιγη; Ηιγη Σιδε Γαυγε − Ηιγη; ∆ισχηαργε Αιρ − Ωαρµ; Συχτιον (λοω) Σιδε Ηοσε − Σωεατινγ ορ Φροστ βυιλδ υπ.
● Εξπανσιον ϖαλϖε (ΤΞ) ϕαµµεδ οπεν ανδ νοτ µοδυλατινγ, χαυσινγ φλοοδινγ οφ εϖαπορατορ ωιτη ρεφριγεραντ. Τηισ ισ νορµαλλψ ρελατεδ το ινχορρεχτ ποσιτιονινγ οφ τεµπερατυρε σενσινγ βυλβ ορ φορειγν µατεριαλ ανδ µοιστυρε εντρψ χαυσινγ ρυστ φορµατιονσ.
Λοω Σιδε Γαυγε − Λοω το ςαχυυµ; Ηιγη Σιδε Γαυγε − Λοω; ∆ισχηαργε Αιρ − Σλιγητλψ χοολ; Εξπανσιον ςαλϖε − Σωεατινγ ορ Φροστ βυιλδ υπ.
● Εξπανσιον ϖαλϖε (ΤΞ) ϕαµµεδ χλοσεδ, ινσυφφιχιεντ ρεφριγεραντ φλοω το συχτιον σιδε οφ τηε χοµπρεσσορ. Τηισ ισ νορµαλλψ ρελατεδ το τηε ΤΞς σενσινγ βυλβ µαλφυνχτιον, δισχοννεχτεδ φροµ τυβε, φορειγν µατεριαλ ιν ΤΞς ορ µοιστυρε εντρψ χαυσινγ ρυστ φορµατιονσ.
Οριφιχε Τυβε Βλοχκεδ (ΧΧΟΤ Σψστεµ)
400
300
3
200
4
LOW
2
1500
6 7
0
0
1 -100
15
1000
1
100
2000
500
5
10
600
700
20
HIGH
25
5
500
30
8
BAR KPa
2500
3000
35 800
BAR KPa
0
3500
Εξπανσιον ςαλϖε (ΤΞ) ρεµαινσ οπεν (ΧΧΤΞς σψστεµ)
400
300
3
200
4
LOW
2
1500
0
7 0 1 -100
15
1000
6
1
100
2000
500
5
10
600
700
500
20
HIGH
5
25 30
8
BAR KPa
2500
3000
35 800
0
BAR KPa
3500
Εξπανσιον ςαλϖε (ΤΞ) ρεµαινσ χλοσεδ (ΧΧΤΞς σψστεµ)
Air Conditioning Training Manual
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INDEX
Servicing ΠΡΟΒΛΕΜ 400
300
3
200
4
LOW
2
1500
10
600
7
700
20
15
1000
6
0
0
2000
500
5
1
100
ΧΟΝ∆ΙΤΙΟΝ
HIGH
30
3000
35
BAR KPa
-100
25
5
500
8
1
2500
BAR KPa
0
800
3500
Χονδενσερ Μαλφυνχτιον ορ Οϖερχηαργε (ΧΧΤΞς/ΧΧΟΤ Σψστεµ)
400
300 200
LOW
2
1500
5
10
600
6 7
0
0
15
1000
1
100
2000
500
4
3
700
500
20
BAR KPa
-100
25 30
8
1
2500
HIGH
5
3000
35
BAR KPa
0
800
3500
Τεµπερατυρε Χοντρολ Σωιτχη (δε−ιχινγ χοντρολ) (ΧΧΤΞς Σψστεµ)
400
300
3
200
4
LOW
2
1500
0
7 0 1 -100
15
1000
6
1
100
2000
500
5
10
600
700
500
20
HIGH
5
25 30
8
BAR KPa
2500
3000
35 800
0
BAR KPa
3500
Λοω Σιδε Γαυγε − Λοω το Νορµαλ; Ηιγη Σιδε Γαυγε − Ηιγη; ∆ισχηαργε Αιρ − Ωαρµ; Ηιγη Σιδε Τυβεσ − ςερψ Ηοτ; Χοµπρεσσορ Χλυτχη − Χουλδ χοντινυαλλψ χψχλε ον τηε ηιγη πρεσσυρε σωιτχη.
ΧΑΥΣΕ ● Ρεφριγεραντ οϖερχηαργε; ● Ενγινε ορ χονδενσερ φαν νοτ οπερατινγ; ● Χονδενσερ φινσ χλογγεδ ωιτη δεβρισ; ● Νο σεαλινγ φοαµ βετωεεν χονδενσερ & ραδιατορ; ● Οβστρυχτιον ιν φροντ οφ χονδενσερ εγ. βυλλ βαρ, ινσεχτ σχρεεν; ● Φαν βελτ σλιππαγε; ● Ραδιατορ οϖερ ηεατινγ.
Λοω Σιδε Γαυγε − Λοω το Νορµαλ; Ηιγη Σιδε Γαυγε − Νορµαλ; ∆ισχηαργε Αιρ − ςερψ χολδ τηεν γοεσ ωαρµ; Εϖαπορατορ − Φρεεζεσ υπ; Αιρ Φλοω − Ρεστριχτεδ ωηεν εϖαπορατορ φρεεζεσ υπ ορ; χοµπρεσσορ χψχλεσ Ον ανδ Οφφ τοο φαστ.
● Φαυλτψ τηερµοστατιχ σωιτχη.
Λοω Σιδε Γαυγε − Ηιγη; Ηιγη Σιδε Γαυγε − Ηιγη; Αφτερ Οριφιχε Τυβε − Ωαρµ; Αχχυµυλατορ − Ωαρµ.
● Ρεφριγεραντ βψ−πασσινγ τηε οριφιχε τυβε. ● Ο∏ ρινγσ ον οριφιχε τυβε δαµαγεδ ορ µισσινγ;
Οριφιχε Τυβε Βψπασσ (ΧΧΟΤ Σψστεµ)
Air Conditioning Training Manual
Page 96
Servicing PROBLEM 400
300
3
200
4
LOW
2
1500
1 -100
15
1000
6 7
0
0
2000
500
5
1
100
CONDITION
10
600
700
20
HIGH
25
5
500
30
8
BAR KPa
2500
3000
35 800
BAR KPa
0
3500
CAUSE
Low Side Gauge Low; High Side Gauge Low; Discharge Air Cool; Accumulator Warm;
● Refrigerant leak from system or normal refrigerant loss over a period of years in operation. ● Refrigerant undercharge
Low Side Gauge High; High Side Gauge Low; Discharge Air Warm; Compressor Not operating;
● Electrical component open circuit; ● Thermostat; ● Pressure switch; ● Clutch coil; ● Fuse; ● A/C switch; ● Blown switch; ● Wiring; ● No power to compressor clutch system. Not operating pressure normally. Equal appr. 500600 kpa high & low side
Refrigerant Loss (CCOT System)
400
300
3
200
4
LOW
2
1500
7 0
0
15
1000
6
1
100
2000
500
5
700
BAR KPa
-100
25
5
500
30
8
1
2500
HIGH
10
600
20
3000
35
BAR KPa
0
800
3500
Note Both high and low pressure readings will be the same Electrical Fault (CCTX/CCOT System)
400
300
3
200
4
LOW
2
1500
0
7 0 1 -100
15
1000
6
1
100
2000
500
5
10
600
700
500
20
HIGH
5
30
8
BAR KPa
2500
25 3000
35 800
0
BAR KPa
3500
Low Side Gauge Low; High Side Gauge Low; Discharge Air Slightly Cool; High Side Tubes Cool and showing signs of sweating or moist build up ot the point after the point of restriction;
Restriction in High Side of System (CCTX/CCOT System)
Air Conditioning Training Manual
● Foreign material causing blockage between the compressor outlet and evaporator inlet (high side) ● No or very little refrigerant flow to suction (low) side of compressor. Note - Compressor - Noisy, fast cycling depending if the high pressure switch is before or after the restriction. Page 97
INDEX
Servicing ΠΡΟΒΛΕΜ 400
300
3
200
4
LOW
2
1500
0
7 0 1 -100
15
1000
6
1
100
2000
500
5
10
600
700
500
20
HIGH
5
25 30
8
BAR KPa
2500
3000
35 800
0
BAR KPa
3500
Εξχεσσιϖε Μοιστυρε (ΧΧΤΞς/ΧΧΟΤ Σψστεµ)
ΧΟΝ∆ΙΤΙΟΝ
ΧΑΥΣΕ
Λοω Σιδε Γαυγε − Νορµαλ το ςαχυυµ; Ηιγη Σιδε Γαυγε − Νορµαλ; ∆ισχηαργε Αιρ − Βεχοµεσ ωαρµερ ασ τηε λοω σιδε χψχλεσ το α ϖαχυυµ; Συχτιον (λοω) Σιδε Ηοσε − Ωιλλ φροστ ιν τηε χασε οφ α ΧΧΟΤ σψστεµ. εγ. αχχυµυλατορ.
● Μοιστυρε χαν φρεεζε ωιτηιν τηε εξπανσιον ϖαλϖε ανδ χαυσε βλοχκαγεσ τηρουγη ρυστ φορµατιον
Air Conditioning Training Manual
Page 98
Servicing
INDEX
Diagnostic Tips Blockage - A/C System A very useful diagnostic aid is the ‘Feel Test’. As the test implies it is a matter of quite simply feeling tubes and components for temperature drops, indicating possible blockage location. By this stage you would be aware of what side of the A/C system should be hot and what side should be cold. But what also happens with the pressure gauge reading, sometimes they don’t make sense.
The location of the charging ports in relation to the A/C system must be taken into consideration. A pressure gauge reading could be high or low depending on what side of the charge port the blockage is located. Use the ‘Feel Test’ as well as the pressure gauge readings.
Normal System ● High side - Hot; ● Low side - Cold
Indicates Blockage.
,, ,,
Blockage - High Side (after charge port) ● High side pressure - High; ● Low side pressure - Low to normal; ● High pressure switch will not deactivate the A/C system, low pressure switch might; ● Compressor noisy; ● High side hose very hot before blockage; ● High side hose very cool to warm after blockage.
Air Conditioning Training Manual
, , Page 99
Servicing
INDEX
Diagnostic Tips Blockage - High Side (before charge port) ● High side pressure - Low; ● Low side pressure - Low to normal; ● High pressure switch will not deactivate the A/C system, low pressure switch might; ● Compressor noisy; ● High side hose very hot before blockage; ● High side hose very cool to warm after blockage.
Blockage - Low Side (after charge port) ● High side pressure - Low; ● Low side pressure - High; ● Low pressure switch will deactivate the A/C system; ● Frosting of the low side hose/fittings before the blockage.
Blockage - Low Side (before charge port) ● High side pressure - Low; ● Low side pressure - Low to vacuum; ● Low pressure switch will deactivate the A/C system; ● Frosting of the low side hose/fittings before the blockage.
Air Conditioning Training Manual
,, Frosted Hose
,, Frosted Hose
,, Page 100
INDEX
Servicing Diagnostic Tips Blockage - Orifice Tube (CCOT system) ● High side pressure - Low; ● Low side pressure - Low to vacuum; ● Low pressure switch will deactivate the A/C system; ● Frosting of the tube after the orifice tube.
Frosted Tube
Low to Zero
Low
,,
Cool Warm
Cool
Warm
Orifice Tube
Blockage - Receiver Drier ● High side pressure - High; ● Low side pressure - Low to Vacuum; ● Low pressure switch should deactivate the A/C system; ● If the blockage is in the receiver drier itself, the outlet tube will be frosted.
Frosted Tube
,,
Checking refrigerant charge - CCOT system Run the A/C system, place one hand at the outlet side of the orifice tube and one hand on top of the accumulator. If the temperature of the accumulator is higher than the temperature after the orifice tube, then the refrigerant charge is not to specification. Add 150gms and recheck.
,, Orifice Tube
Air Conditioning Training Manual
Page 101
INDEX
Servicing Diagnostic Tips Blockage - Condenser A change of state, where high pressure vapour forms into a high pressure liquid during the movement through the condenser, takes place within approximately the first 1/3 of the condenser. With this change of state a slight (depending on ambient temperature) temperature change takes place. Using your finger, follow the tube(s) of the condenser (avoid burning your skin), you can feel where the change of state takes place. This change will however be quite subtle. But if you feel the difference in temperature before approximately the first 1/3 , a blockage maybe present.
With the parallel flow design condenser, refrigerant flows through more than one tube so the possibility exists that the condenser will operate sufficiently in lower ambient. But when the ambience increases and greater refrigerant flow is required, a blockage in one tube will cause problems such as poor performance and excessive discharge pressures.
High Pressure Vapour
Indicates Blockage
High Pressure Vapour
Indicates Blockage
Air Conditioning Training Manual
High Pressure Liquid
High Pressure Liquid
Page 102
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