Thermostatically Controlled Electric Fans: Testing

If fan is not operating properly, disconnect fan motor wire connector and connect it with 14 gauge wire to a good 12-volt battery. If fan runs, motor is all right, indicating car battery, radiator fan switch (Chrysler), coolant relay, timer relay (Ford), coolant temperature switch (GM) or A/C relay (all models) may be defective. If fan motor does not run when connected directly to a good battery, replace fan motor.