Radiator Cooling Fan Motor: Testing and Inspection

Fan control is accomplished two ways. A pressure transducer on the compressor discharge line sends a signal to the Powertrain Control Module (PCM) which will activate the fan. In addition to this control, the fan is turned on by the temperature of the coolant which is sensed by the coolant temperature sensor which sends the message to the PCM. The fan will not run during cranking until the engine starts no matter what the coolant temperature is.

CAUTION: The solid state fan relay is attached to the left frame rail near the lower radiator support. The relay bracket, and fastener are used to dissipate heat from the relay. Ensure the relay is properly attached to prevent the following:

- Intermittent engine overheating.
- Relay "thermal" shutdown, or relay damage.

For Diagnosis TC-14A RAD Fan Control Relay Circuit