The condenser is a heat exchanger that cools, condenses and liquefies the high-temperature, high-pressure gas refrigerant sent from the compressor. The quantity of heat emitted from the condenser equals the sum of the heat quantity absorbed in the evaporator, and the heat quantity added by compression performed in the compressor. High-temperature, high-pressure refrigerant discharged from the compressor is cooled and condensed by ambient air while passing through the condenser, resulting in a high-temperature, high-pressure liquid refrigerant.


Low-temperature, low-pressure gas refrigerant that has been vaporized in the evaporator through the extraction of heat from the vehicle interior is suctioned and compressed by the compressor. The compressor then sends a high-temperature, high-pressure gas to the condenser that can be readily liquefied. The car A/C system compressor is driven* by a belt from the engine and a magnetic clutch

Expansion Valve

- The expansion valve causes rapid refrigerant expansion by injecting high-temperature, high-pressure liquid refrigerant through a small orifice, in effect creating a low-temperature, low-pressure mist refrigerant.
- The expansion valve adjusts the refrigerant quantity according to the state of refrigerant vaporization in the evaporator. As a result, conditions are maintained under which liquid refrigerant takes heat from the surrounding air so that refrigerant is continuously evaporated at the evaporator outlet.


- The evaporator consists of a tank, tubing, and fins. Refrigerant that has been liquefied in the condenser, and then changed into a low-temperature, low-pressure mist by the expansion valve takes heat from the surrounding air and is vaporized in the evaporator. As a result, the evaporator itself is in a low-temperature state.
- Warm air circulating within the vehicle (or that has been drawn in from outside the vehicle) is cooled by passing over the evaporator, which in turn cools the passenger compartment. In addition, when warm air comes into contact with the evaporator fins and is cooled to or below the dew point temperature, moisture within the air is condensed to form water droplets. These water droplets are discharged outside the vehicle by a drain hose.