Electric radiator-fan motors are turned on either by the ignition switch and will continue rotating while the engine is working – or by a thermostatic switch.
Motors controlled by thermostat do not signal the fan to run until the engine rises above normal operating temperature, and would then switch off the fan when it has cooled down again.
To ascertain if the fan is working, listen for it cutting in and out, and be checking the temperature gauge.
However if the engine shows signs of overheating, pull over and look to see if the fan is functioning. When checking for this, be sure to keep your engine running if your car is operated by the ignition switch.
But where there is a thermostatic switch in the circuit, keep the car on and let it run at fast idle. Without air flowing through the radiator, it will soon warm the engine up to the temperature at which the fan should start fanning.
The fan assembly usually has but three components – fan motor, thermostatic switch, and relay. If the fan is not working, the faults may be from these units and or the wiring to them may be faulty… Here are steps on how to repair the fault
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