Radiator Cooling Fan Motor Relay: Description and Operation

The PCM controls the two coolant fans using three relays. The PCM will command one or both depending upon several operating conditions. If the coolant temperature sensor indicates high engine temperature, the PCM will energize one or more relays to turn "ON" the fan. If the A/C is engaged, the PCM will turn the coolant fan "ON" to cool the condenser as well as the radiator. Some fault codes will cause the PCM to turn on the fan. Above certain vehicle speeds, the PCM will de-energize the fan relay since at higher road speeds there is ample air flow.