Radiator Cooling Fan Temperature Sensor / Switch: Description and Operation

The Cooling Fan Temperature Switch is normally closed. When the Ignition Switch is in the RUN position and the coolant temperature is below 91~C (196~F), current flows through the 30A HEATER circuit breaker energizing the Cooling Fan Relay coil. When the Cooling Fan Relay is energized, the contacts are held open. When the coolant temperature rises above 91~C (196~F), the Cooling Fan Temperature Switch opens, de-energizing the Cooling Fan Relay and closing the Cooling Fan Relay contacts by spring pressure. When the Cooling Fan Relay contacts close, current flows through the 20A COOLING FAN fuse to operate the Cooling Fan Motor.

If the car is equipped with air conditioning, the Cooling Fan Relay coil is de-energized by the WAC Relay allowing the Cooling Fan to run continuously when the A/C system is operating.