It can be easy to be fooled into believing that the fan isn’t working, so carry out a visual check to be absolutely certain. Do this by lifting the hood and listening carefully. The fan might be on but newer engines can be very quiet, so you don’t hear them when you’re sitting inside your vehicle.
Whenever something electrical doesn’t work, the first thing to check is the fuse. If you don’t know where the fuses are in your vehicle, consult your owner’s manual to see which fuse controls the cooling system. Make sure the fuse for the radiator fan is intact. If it is not, replace it immediately, and this should take care of the problem.
2. Fan Wires
If the engine is heating but the fan isn’t kicking in, check the fan wires. Start by unplugging the wires. There will be two wires of positive and negative feed. They should be putting out around 12 volts of direct current. Use a voltmeter to check that there is current present. If there is not, you need to check both the wires and the fan relay to see if replacement is required.
3. Temperature Sensor
The temperature sensor determines when the radiator fan comes on by reading the cooling system temperature. If the sensor isn’t working, your fan won’t come on because it won’t know that the temperature is hot enough to require activation, which can frequently lead to overheating.
The sensor is usually located in the car thermostat cover. To check it, disconnect the wires from the sensor and touch them together. If this starts the fan, the sensor is faulty and will need to be replaced. Check your service manual to make sure exactly where the temperature sensor is on your car.
4. Coolant Level
Check the coolant level in your engine. The simplest way to do this is to look at the reservoir in the engine. It will be marked with maximum and minimum levels. Always make sure the coolant level is up near the maximum level to avoid possible overheating.
5. Fan Clutch
The fan clutch is the assembly that holds the radiator fan to the engine and makes it turn. If this burns out or fails, you’ll need to replace it. There are springs within the fan clutch that can wear out or corrode over the years. If everything else seems to be fine, the fan clutch is the most likely cause of radiator fan failure.