Radiator Cooling Fan Motor: Testing and Inspection

SYSTEM TEST

1. Start engine and run until it reaches normal operating temperature.
2. Monitor coolant temperature using suitable thermometer and observe cooling fan operation.
3. Cooling fan should begin to operate when coolant temperature reaches 186-192°F., and fan should stop running when coolant temperature drops to 178-183°F.
4. If fan fails to operate, proceed as follows:
a. Ground white/blue fan test lead located in harness at left rear of engine compartment.
b. If fan operates, replace thermosensor and recheck system operation.
c. If fan fails to operate, check for blown fuse, defective relay, damaged or disconnected wiring, disconnected fan ground lead or defective fan motor.
5. On models with A/C, place control in maximum cooling position.
6. If cooling fan does not operate when compressor clutch is engaged, check for open circuit between fan relay and A/C switch, defective switch or defective compressor clutch diode.

COMPONENT TESTING

Fan Motor

1. Disconnect electrical connector to fan motor.
2. Connect battery voltage to terminal using suitable jumper wire.
3. If fan fails to operate, check ground strap connection, Fig. 1, and repair as needed.
4. If ground is satisfactory, motor is defective.

Fan Relay

1. Disconnect electrical connector and remove relay. Fan relay is located in left front of engine compartment above battery.
2. Connect ohmmeter between white/black and white/green wire terminals on relay.
3. Meter should indicate no continuity.
4. Connect battery voltage across white and white/blue wire terminals on relay.
5. With relay energized, ohmmeter should indicate continuity between white/black and white/green wire terminals.

Fig. 1 Cooling fan & thermosensor installation:

Thermosensor

1. Drain cooling system and remove thermosensor from radiator, Fig. 1.
2. Connect suitable ohmmeter between sensor terminals.
3. Heat thermosensor in suitable solution while observing ohmmeter.
4. Meter should indicate continuity when temperature reaches 186-192°F.
5. Allow sensor to cool while observing meter. Meter should indicate no continuity as temperature drops below 178-183°F.
6. If sensor fails to operate as outlined, sensor is defective.