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AIR CONDITIONING

AIR CONDITIONING 1B-1 HEATING AND AIR CONDITIONING SECTION 1B AIR CONDITIONING Caution: When fasteners are removed, always reinstall them at the same location from which they were removed. If a fastener needs to be replaced, use the correct part number fastener for that application. If the correct part number fastener is not available, a fastener of equal size and strength (or stronger) may be used. Fasteners that are not reused, and those requiring thread locking compound, will be called out. The correct torque values must be used when installing fasteners that require it. If the above conditions are not followed, parts or system damage could result.

Contents GENERAL DESCRIPTION ...................................1B-2 Air Conditioning Refrigerant Cycle Construction ...1B-2 Compressor.......................................................1B-3 Magnetic Clutch.................................................1B-4 Condenser.........................................................1B-4 Receiver/Drier....................................................1B-4 Dual Pressure Switch (for GCC and Taiwan)....1B-5 Triple Pressure Switch (for Australia)................1B-5 Evaporator.........................................................1B-6 Expansion Valve................................................1B-6 Electronic Thermostat........................................1B-7 Refrigerant Line.................................................1B-7 Service Charge Valves......................................1B-7 Air Conditioning Parts........................................1B-8 ON-VEHICLE SERVICE .....................................1B-10 Precautions for Refrigerant -134a (R-134a) Air Condi- tioning System.................................................1B-10 Precautions for Replacement or Repair of R-134a Air Conditioning Parts ...........................................1B-12 Compressor.....................................................1B-20 New Compressor Installation...........................1B-21 Condenser Assembly (Except 4HK1-TC Engine Mod- el For Australia) ...............................................1B-22 Condenser Assembly (4HK1-TC Engine Model For Australia) .........................................................1B-23 Receiver / Drier (Except 4HK1-TC Engine Model For Australia) .........................................................1B-24 Receiver / Drier (4HK1-TC Engine Model For Austra- lia)....................................................................1B-25 Pressure Switch...............................................1B-26 Evaporator Assembly ......................................1B-27 Evaporator Core / Expansion Valve (LHD Model) ...1B-30 Evaporator Core / Expansion Valve (RHD Model) ..1B-32 A/C Switch.......................................................1B-34 Refrigerant Line (Except 4HK1-TC Engine Model For Australia) .........................................................1B-36 Refrigerant Line (4HK1-TC Engine Model For Austra- lia)....................................................................1B-37

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Air Conditioning Refrigerant Cycle Construction

1B-2 AIR CONDITIONING GENERAL DESCRIPTION Caution: This Vehicle is equipped with Refrigerant-134a (R-134a) air conditioning system. R-134a and A-12 systems require different types of lubricating oil. Components designed solely for use with one re- frigerant and oil type must never be interchanged with components designed solely for use with another refrigerant and oil type. Refer to “ON-VEHICLE SERVICE” for Precautions for R-134a Air Conditioning system in this section. Air Conditioning Refrigerant Cycle Construction N1A0045E

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Compressor

AIR CONDITIONING 1B-3 Legend A. High pressure, high temperature gas 6. Evaporator assembly B. High pressure, high temperature mixture of gas and liquid 7. Expansion valve 8. Temperature sensor C. High pressure, medium temperature liquid 9. Evaporator core D. Low pressure, low temperature mixture of liquid and gas 10. Blower motor 11. Heater unit E. Low pressure, low temperature gas 12. Heater core 1. Compressor 13. Temp. control door (Air mix door) 2. Magnetic clutch 14. MODE (DEF) control door 3. Receiver / Drier 15. MODE (VENT) control door 4. Pressure switch 16. MODE (HEAT) control door 5. Condenser 17.

Electronic thermostat The refrigeration cycle includes the following four pro- cesses as the refrigerant changes repeatedly from liquid to gas and back to liquid while circulating. The high temperature, high pressure gas coming from the compressor is cooled and liquefied by the condenser with outside air and accumulated in the receiver/drier. The heat radiated to the outside air by the high temper- ature, high pressure gas in the compressor is called heat of condensation. This is the total quantity of heat (heat of vaporization) the refrigerant removes from the vehicle interior via the evaporator and the work (calcu- lated as the quantity of heat) performed for compres- sion.

Evaporation The refrigerant is changed from a liquid to a gas inside the evaporator. The refrigerant mist that enters the evaporator vaporizes readily. The liquid refrigerant re- moves the required quantity of heat (latent heat of va- porization) from the air around the evaporator core cooling fins and rapidly vaporizes. Removing the heat cools the air, which is then radiated from the fins and lowers the temperature of the air inside the vehicle. The refrigerant liquid sent from the expansion valve and the vaporized refrigerant gas are both present inside the evaporator and the liquid is converted to gas.

With this change from liquid to gas, the pressure inside the evaporator must be kept low enough for vaporization to occur at a lower temperature. Because of that, the vaporized refrigerant is sucked into the compressor. Expansion The expansion valve lowers the pressure of the refriger- ant liquid so that it can easily vaporize. The process of lowering the pressure to encourage va- porization before the liquefied refrigerant is sent to the evaporator is called expansion. In addition, the expan- sion valve controls the flow rate of the refrigerant liquid while decreasing the pressure.

That is, the quantity of refrigerant liquid vaporized inside the evaporator is determined by the quantity of heat which must be removed at a prescribed vaporization temperature. It is important that the quantity of refriger- ant be controlled to exactly the right value. Compression The refrigerant is compressed by the compressor until it is easily liquefied at normal temperature. The vaporized refrigerant in the evaporator is sucked into the compressor. This action maintains the refriger- ant inside the evaporator at a low pressure so that it can easily vaporize, even at low temperatures close to 0 ° C (32 ° F).

Also, the refrigerant sucked into the compressor is com- pressed inside the cylinder to increase the pressure and temperature to values such that the refrigerant can eas- ily liquefy at normal ambient temperatures. Compressor The compressor performs two main functions: It compresses low-pressure and low-temperature refrig- erant vapor from the evaporator into high-pressure and high-temperature refrigerant vapor to the condenser. And it pumps refrigerant and refrigerant oil through the A/C system. This vehicle is equipped with a swash plate type com- pressor (DKS-15 D Type, DKS-13 CH Type for Taiwan only). Swash plate compressors have a swash (slanted) plate mounted on the shaft.

When the shaft turns, the rotation of the swash plate is converted to reciprocating piston motion which sucks in and compresses the refrigerant gas. Shaft seal (Lip type) is installed between the valve plate and shaft a cylinder head to prevent refrigerant gas leaks. A specified amount of compressor oil is contained in the oil pan. Condensation The refrigerant inside the condenser is cooled by the outside air and changes from gas to liquid.

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Receiver/Drier

1B-4 AIR CONDITIONING This oil is supplied to the cylinders, bearings, etc., by an oil pump which is connected to the swash plate shaft. With some compressors the differential between the in- take pressure and discharge pressure generated while the compressor is operating is used for lubrication in- stead of an oil pump. The specified amount of compressor oil is 180cc (5.0 Imp fl oz). The oil used in the R-134a system compressor differs from that used in R-12 systems. Also, compressor oil to be used varies according to the compressor model. Be sure to avoid mixing two or more different types of oil.

If the wrong oil is used, lubrication will be poor and the compressor will seize or malfunction. (Refer to “ON-VEHICLE SERVICE” for Precautions for R-134a Air Conditioning System in this section) The magnetic clutch connector is a waterproof type. A condenser (1) may malfunction in two ways: it may leak, or it may be restricted. A condenser restriction will result in excessive compressor discharge pressure. If a partial restriction is present, the refrigerant expands af- ter passing through the restriction. Thus, ice or frost may from immediately after the restric- tion. If air flow through the condenser or radiator is blocked, high discharge pressures will result.

During normal condenser operation, the refrigerant outlet line will be slightly cooler than the inlet line. The vehicle is equipped with the condenser of the paral- lel flow type condenser. A larger thermal transmission area on the inner surface of the tube allows the radiant heat to increase and the ventilation resistance to de- crease. Magnetic Clutch The compressor (1) is driven by the drive belt from the crank pulley of the engine. If the compressor is activated each time the engine is started, this causes too much load to the engine. The magnetic clutch (2) transmits the power from the engine to the compressor and activates it when the air conditioning is “ON”.

Also, it cuts off the power from the engine to the compressor when the air conditioning is “OFF”. (Magnetic clutch repair procedure can be found in Section 1D) 1 N1A0047E 1 2 Receiver/Drier The receiver/drier performs four functions; As the quantity of refrigerant circulated varies de- pending on the refrigeration cycle conditions, suffi- cient refrigerant is stored for the refrigeration cycle to operate smoothly in accordance with fluctua- tions in the quantity circulated. The liquefied refrigerant from the condenser is mixed with refrigerant gas containing air bubbles. If refrigerant containing air bubbles is sent to the ex- pansion valve, the cooling capacity will decrease considerably.

Therefore, the liquid and air bubbles are separated and only the liquid is sent to the ex- pansion valve. N1A0046E Condenser The condenser assembly in front of the radiator, which carry the refrigerant and cooling fins to provide rapid transfer of heat. Also, it functions to cool and liquefy the high-pressure and high-temperature vapor sent from the compressor by the radiator fan or outside air. The receiver/drier utilizes a filter and dryer to re- move the dirt and water mixed in the cycling refrig- erant. A receiver/drier may fail due to a restriction inside the body of the unit. A restriction at the inlet to the receiver/ drier will cause high pressures.

Outlet restrictions will be indicated by low pressure and little or no cooling. An excessively cold receiver/drier outlet may indicate a restriction.

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