Auto A/C Terms - Glossary
Blower Fan

Every automotive A/C system cools the vehicle by removing the heat from the air entering the vehicle. Outside air enters the passenger compartment of the vehicle with the assistance of the blower fan. That fan is an electric motor driven fan which forces outside air through the evaporator and duct assembly into the car. Typically, the blower fan is located under the hood of the vehicle on the passenger side, mounted on the evaporator case.

When operating, the blower fan is forcing hot outside air over the cold evaporator. The heat in the air is transferred from the air to the cold refrigerant, because heat will always flow from areas of high temperature to areas of low temperature.

The blower fan also used when heating is required. It forces air into the vehicle to be heated and help provide complete temperature control. In cases where heat is required, the air exiting the evaporator is then passed over the heater core to be heated. In cases where moderate heat or temperature control is needed, the air delivery is split. Some air exits the evaporator and moves directly into the vehicle while the rest is directed over the heater. That mixing is accomplished with the blend door in order to provide maximum temperature control and passenger comfort.

The blower fan continues to force the heated or cooled air through the ducts and out any number of vents inside the vehicle. Those vents include floor, defrost and dash vents.