Evaporator Core: Description and Operation

The evaporator is a device which cools and dehumidifies the air before it enters the passenger compartment. Low pressure liquid refrigerant flows through the expansion valve into evaporator. The heat in the air passing through the evaporator core is lost to the cooler surface of the core, thereby cooling the air. As the process of heat loss from the air to the evaporator core surface is taking place, the moisture (humidity) in the air condenses on the outside surface of the evaporator core and is drained off as water. Evaporator pipes are now wrapped with mastic for system noise reduction.