Control Module HVAC: Description and Operation

Fan Control Unit Diagram:

FAN CONTROL UNIT OPERATION
The fan control unit makes calculations based on signals from the water temperature sensor. It then controls the operation of the radiator fan, condenser fan and A/C system.

Fan Control Unit Operating Ranges:

TEMP 1:
When radiator coolant temperature is above 183°F (84°C), the control unit turns Tr1 ON, then the radiator fan runs (Low), and condenser fan runs (Low).
TEMP 2:
When radiator coolant temperature is above 194°F (9O°C), the control unit turns Tr2 ON, then the radiator fan runs (High), and the condenser fan runs (High).
TEMP 3:
When radiator coolant temperature is above 268°F (109°C), the control unit turns Tr3 OFF, then stops the A/C compressor.