You need to replace a faulty fan as soon as possible to keep from overheating and causing other damage. Running your engine without a working fan will lead to disaster. Here’s what you need to know about fan issues and how to fix them.
Checking the Fan Motor
An electric fan motor runs while the engine is running, and it is turned on by the ignition switch or a thermostatic switch. The thermostatic switch does not turn the fan on until the temperature of the engine coolant rises. Once the temperature is back down to normal, the switch turns the fan off.
You can listen for the fan, and if you see any overheating, stop, leave the engine on and lift the hood. With an ignition switch motor, the fan should be turning. If it is not, then you may have a fan motor problem on your Mazda.
- Before you test anything else, check the fuse box to see if there is a blown fuse.
- If you find that the fuse is okay, then you want to turn the ignition to the ON position and test for current at the motor terminals by using a circuit tester.
- On thermo-switch motors, connect the motor’s feed terminal to the positive battery terminal.
- The motor is bad if you have current going to the motor.
- On the thermo-switch, there may be a problem with the earthing point. Make sure that the earthing point is tight and clean. Make sure that the thermo-switch works. The switch is within the circuit, and you can test it by putting the vehicle in a fast idle. The radiator will warm up quickly, and at that point, the fan should start.
- If it does not start, you may have a problem in the motor, the thermo-switch or the relay.
Changing the Motor
Should you find that the motor needs to be replaced, here are the instructions for changing out the fan motor on your Mazda.
- Disconnect the battery
- Remove the wiring terminals or plug from the motor
- Take the wires off the shroud or body.
- Take the motor and the fan off. You may need to take the shroud off to get the motor out.
- Take them apart and clean the reusable parts.
- Check your new motor by connecting it directly to the battery. It may buck and spark when you connect it.
- Reinstall the fan and motor.
- Reverse the steps.
Check the Switch
With the ignition in the ON position, remove the connections on the thermo-switch and touch them together. If the motor works, then the switch is the problem.
Should the motor still not work, you can check the current to the switch with a circuit tester. Put it on the feed wire. There should be a light, but if it does not light, then use the owner’s manual to trace the thermo-switch to the power. Look for problems in the wiring.
If you do get a light, then follow the lead to the relay and the terminals. Clean and tighten anything that is dirty or loose.
Changing the Thermo-Switch
- This switch is usually in the radiator bottom tank, in the cylinder head or the thermostat housing. A switch in the radiator requires you to drain the tank until you can see the switch. Put the old fluids into a clean container, so you can reuse it.
- There may be a rubber cover on the back of the switch. Take it off and disconnect any electrical connections.
- Unscrew the switch using a spanner. Be careful not to distort it if it is tight. Put a new sealing washer on it when you put the new one in.
Check the Relay
There are a couple tests you can do in order the check the relay for problems.
- Test the relay for problems by turning the ignition to the ON position. Put a screwdriver over the two terminals on the thermo-switch in order to short circuit it. Leave the leads connected. You may hear it click.
- Turn the ignition to the ON position. Use a test lamp or a circuit tester to test for current at the live lead.
- If you find current here, but none at the terminal to the fan motor, then the relay is bad. Replace it.
This should help you diagnose and repair your cooling fan problem in your Mazda. However, if you continue to have problems with it, then consult the technicians at your local dealership.