Evaporator Core: Description and Operation

A/C EVAPORATOR
The evaporator is located in the heater housing, behind the instrument panel. The evaporator is positioned in the housing so that all air that enters the housing must pass over the fins of the evaporator coils before it is distributed through the system ducts and outlets. However, air passing over the evaporator coil fins will only be conditioned when the compressor is engaged and refrigerant is circulating through the evaporator coil tubes.

Refrigerant enters the evaporator from the expansion valve as a low-temperature, low-pressure liquid. As air flows over the fins of the evaporator, the humidity in the air condenses on the fins, and the heat from the air is absorbed by the refrigerant. Heat absorption causes the refrigerant to boil and vaporize. The refrigerant becomes a low-pressure gas before it leaves the evaporator.

The evaporator cannot be repaired and, if faulty or damaged, it must be replaced.