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.