The evaporator cools and dehumidifies the air before the air enters the passenger compartment. Low-pressure, low temperature liquid/vapor refrigerant goes through the following process:

1. Enters the evaporator.
2. Flows through the tubing.
3. Evaporates.
4. Exits the evaporator as low-pressure, low temperature, mostly vapor refrigerant

As the refrigerant evaporates, the refrigerant absorbs heat from the air flowing over the evaporator. As the process of heat loss from the air to the evaporator core takes place, any moisture (humidity) in the air condenses on the outside surface of the evaporator core. The moisture (humidity) drains off as water.