How to fix a car fan

How the fan is fitted

Here you can get fixing a car fan, Checking the circuit and motor for faults, Changing the fan motor and Checking the new motor ect.

Electric radiator-fan motors are switched on either by the ignition switch – and run while the engine is working – or by a thermostatic switch. Thermostatically controlled motors don’t work the fan until the engine coolant rises above normal operating temperature, and then switch off when it’s cooled down again.

To check that the fan is functioning , listen for it cutting in and out, and watch the temperature gauge. If the engine shows signs of overheating, stop and appearance to see if the fan is functioning . With the sort operated by the ignition switch, keep the engine running.

Where there’s a thermostatic switch within the circuit , start the car and let it run at fast idle. With no airflow through the radiator, it’ll soon warm up to the temperature at which the fan should cut in. The assembly usually has only three components – fan motor, thermostatic (or thermo) switch, and relay. If the fan isn’t working, these units or the wiring to them could also be guilty.

Checking the circuit and motor for faults

Look at the fuse box for a blown fuse. If the fuses are intact, switch on the ignition and use a circuit tester to find if there’s current at the motor terminals. Alternatively, connect the feed terminal on the motor direct to the battery positive terminal if the motor is fed via a thermo-switch.

In either case, if there’s a current at the motor, the motor is at fault. If the thermo-switch doesn’t operate, the earthing point of the circuit could also be faulty. make sure the earthing point is clean and tight. Check also the functioning of the thermo-switch.

Changing the fan motor

Disconnect the battery , and take off the wiring terminals to the motor or disconnect the plug. Free the wires from clips or other fixings on the fan shroud or nearby bodywork. The motor and fan normally come off as an assembly, but you’ll even have to remove the shroud and sometimes the radiator. Separate the components. Clean the parts that are to be reused, just by degreasing or maybe by repainting.

Checking the new motor

When you fit a replacement motor, check it by connecting its leads on to the battery. be sure to connect the positive (+) and negative (—) leads to the corresponding battery terminals. Take care — the motor will kick as it starts and there’ll be a large spark when it’s connected.

Checking the switch for faults

If the fan motor isn’t at fault, leave the ignition switched on, take the connections off the thermo-switch and briefly touch them together. If the fan motor now works, the switch is faulty. If it doesn’t , check to see that there’s current flowing to the switch by using a circuit tester on the feed wire to the thermoswitch.
If the tester doesn’t light, trace the lead from the thermo-switch back to its power supply; the car handbook may have a wiring diagram. If the tester lights, trace the lead from the thermo-switch through to the relay and check the terminals for tightness and cleanliness. Clean and tighten as necessary.

Changing a thermo-switch

The thermo-switch is normally located within the radiator bottom tank, within the thermostat housing, or within the plate. To remove the switch, drain the radiator (See the way to flush an engine radiator ) until the coolant is below the extent at which it’s fitted. Catch the coolant during a clean container if you plan to reuse it.

If a rubber cover is fitted over the rear of the switch, ease it off, then disconnect the electrical connections. The switch can now be unscrewed from its mounting point with an appropriate spanner. It may, however, be very tight, so lookout to not distort the surrounding metal if it’s fitted in the radiator bottom tank. Always fit a new sealing washer.

Checking the relay for faults

With the ignition switched on, short-circuit the thermo-switch by putting a screwdriver across its two terminals; don’t disconnect the leads. you’ll be ready to hear a click from the relay because it operates. Test for current with a test lamp or circuit tester at the ‘live’ cause the relay — again with the ignition switched on. If there’s current here but, when the thermo-switch is bypassed, none at the terminal for the fan-motor lead, the relay is faulty and must be replaced.


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