K 2500 Suburban 4WD V8-454 7.4L (1994)
Radiator Cooling Fan Motor: Description and Operation
DESCRIPTION
This auxiliary cooling fan circuit consists of a coolant temperature sensor, a relay and the fan. The fan only operates when the ignition is on and
the coolant temperature sensor is above the set temperature.
CIRCUIT OPERATION
Battery voltage is supplied to the Auxiliary Cooling Fan Control Relay by the RED (2) wire at all times and by the PNK/BLK (39) wire when the
Ignition Switch is in RUN or START. When the Auxiliary Cooling Fan Control Temperature Switch closes at 107°C (225°F), the A/C high
pressure switch closes or the A/C Controller is activated, circuit 37 is grounded and the Auxiliary Cooling Fan Control Relay energizes. Battery
voltage is supplied across the Auxiliary Cooling Fan Control Motor and the Auxiliary Cooling Fan operates.
