Radiator Cooling Fan Motor Relay: Description and Operation
RADIATOR FAN RELAYS - PCM OUTPUTThe radiator fan relays are located in the PDC. The inside top of the PDC cover has a label showing relay and fuse location.
The PCM energizes the radiator fans through either the low or high speed radiator fan relay. The PCM controls the ground circuit for the coil side of the relay. Power for both relay coils is supplied through a 10 amp fuse in the PDC. Power for both relay contacts is supplied power through a 40 amp fuse in the PDC.
The PCM monitors the A/C compressor discharge (high side) pressure through the air conditioning pressure transducer. Depending on engine coolant temperature and A/C system high side pressure, both fans operate at either low or high speed.