Evaporator Core: Description and Operation

The evaporator is a device which cools and dehumidifies the air before it enters the passenger compartment. High-pressure liquid refrigerant flows through the expansion tube, becomes a low-pressure liquid, and then enters the evaporator. The heat in the air passing through the evaporator core is transferred to the cooler surface of the core, thereby cooling the air. As the process of heat transfer from the air to the evaporator core surface is taking place, any moisture (humidity) in the air condenses on the outside surface of the evaporator core and is drained off as water. The evaporator is located inside the HVAC module at the front of dash.