Blower Thermo-Switch

Blower Fan Thermo-Switch

Purpose and Operation
A thermoswitch is also used to control the operation of the blower fan. The switch completes a ground circuit to the control head. When engine temperature is below 104°F (40°C) the switch is open and interrupts the ground circuit. This prevents the blower fan from running when the engine is cold and supplying uncomfortable gusts of cold air at low ambient temperatures.

If the Defrost button is pressed, this feature is overridden and the fan starts immediately.