The A/C relay controls the condenser fan and A/C compressor circuits. The relay is controlled by the engine control unit. If the coolant exceeds a certain temperature, the engine control unit turns off the relay, which turns off the air conditioning system. When the engine is started or the vehicle accelerates, the engine control unit turns off the relay, as a result of which the air conditioning system is turned off within 5 seconds.
The fan blows air through the evaporator core, which increases the flow of cool air into the vehicle interior. The fan speed is determined by the position of the fan switch and the resistor pack.
The air conditioning compressor is the primary element of the air conditioning system. If the air conditioning compressor fails, there is no compression and no movement of the refrigerant through the air conditioning circuit. The air conditioning compressor is driven by a belt from the crankshaft pulley.
The A/C compressor clutch engages the compressor. The clutch is electromagnetically controlled.
The condenser is installed in front of the radiator. The condenser fan increases the air flow through the condenser.
The fan/evaporator assembly contains the fan motor, A/C relay, evaporator core and expansion valve.
The evaporator core performs the functions of cooling and dehumidifying the air. When the air is cooled, moisture from the air is deposited on the evaporator and cooled dry air enters the car interior.
The expansion valve allows high pressure liquid refrigerant to expand into the evaporator. The valve passes a certain amount of liquid refrigerant to prevent flooding of the evaporator.
The dehumidified air can be reheated by passing through the heater core. The heater core is heated by the hot coolant passing through it.
The receiver/dryer receives liquid refrigerant from the condenser, where water is removed from it and then the refrigerant enters the evaporator.
The air conditioning system is charged with R-134a refrigerant.