Engine Compartment Fan: Description and Operation

Battery voltage is supplied at all times through fuse 31 and the radiator fan motor to the normally open contacts of the radiator fan HIGH and LOW relays. Battery voltage is also supplied at all times through fuse 24 to the normally open contacts of the engine compartment fan relay. With the ignition switch in ON (II), battery voltage is supplied through fuse 4 and the radiator fan relay coils and through the engine compartment fan relay coil to the fan control unit. When the radiator sensor detects a coolant temperature above 183°F (84°C) it grounds the GRN/BLK wire to energize the radiator fan LOW relay. With the relay contacts closed, the radiator fan motor is grounded through the radiator fan resistor. The fan runs at low speed to remove heat from the coolant. When the radiator fan control sensor detects a coolant temperature above 194°F (90°C), it grounds the BLU/RED wire to energize the radiator fan HIGH relay and the engine compartment fan relay. With the relay contacts closed, the radiator fan motor is grounded and the radiator fan runs at high speed to remove heat from the coolant. The engine compartment fan relay also feeds battery voltage to the engine compartment fan which then runs to remove heat from the engine compartment.