Evaporator General

The evaporator core is used to cool and dehumidify the air before the air enters the passenger compartment.

High pressure liquid refrigerant flows through the expansion (orifice) tube and becomes low pressure refrigerant liquid before entering the 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 a process of heat loss from the air to the evaporator core surface is taking place, any moisture (humidity) in the air condenses on the outside of the evaporator core and is drained off as water. As the air passes through the core, the cooler surfaces absorb the heat, cooling the air. As the air is being cooled, any humidity in the air condenses on the outside of the evaporator core and is drained off as water.