Fan Motor Control and A/C Medium Pressure Switch

Fan Motor relay And A/C Refrigerant Medium Pressure Switch:

PURPOSE
Radiator and condenser fan operation is controlled by the ECU, Based on input from the Engine coolant temperature sensor, air conditioning medium pressure switch and vehicle speed.

FAN OPERATION
If the engine coolant temperature is high and vehicle speed is low, the radiator and condenser fans are turned on at high speed. If vehicle speed is high, the fan speed will be low.

MEDIUM PRESSURE SWITCH OPERATION
The ECU monitors the Engine coolant temperature and A/C refrigerant pressure. If excess refrigerant pressure is detected, with the A/C switch in the on position, both fans are activated (via their respective relays and resistor) at high speed, regardless of vehicle speed.