Heating and Air Conditioning: Description and Operation

Air Conditioning (A/C) System
The A/C system removes heat from the passenger compartment to lower the temperature. Using engine power, the compressor compresses gaseous refrigerant into high temperature/high pressure gas. It then pumps this gas into a condenser unit built onto the vehicle's radiator.

The condenser cools the gas, changing it into high pressure/low temperature liquid refrigerant. The liquid then goes to the receiver/drier which first removes any liquid water and then sends the liquid to an evaporator in the heater unit, inside the passenger compartment.

The evaporator then uses passenger compartment temperature to turn the liquid back into a gas, extracting heat from the passenger compartment. The gas is then sent back to the compressor, and the cycle begins again.

Heater System
Dehumidified air is reheated as it passes through the heater core in the heater unit. The heater is warmed by the engine coolant passing through the tubes of the heater core. Heat is transferred to the core fins and passed off to the air flowing past the fins. The position of the air temperature valve in the air conditioning module determines how much of the total airflow is permitted to pass through the heater. This determines the warmth of the overall air flow that is sent into the passenger compartment.