ProCars Zimbabwe

7 Causes Why Your Radiator Fan is not working

Here is a more detailed list of the most common causes of a radiator fan not coming on.

1. Broken Fuse
A fuse supports almost everything electrical in a car. If there is an electrical surge going towards a piece of electronic equipment, the fuse cuts the electric supply to that particular equipment saving it from destruction. This is what we call a blown fuse.

Here is a more detailed list of the most common causes of a radiator fan not coming on.

A blown fuse is no big deal, and changing one does not cost a lot of money. If your car’s radiator fan is non-functional, check your car’s user manual and locate the fuse for the radiator fan controller or the fan.

2. The fan itself often uses a big fuse of around 50A, while there might also be a separate small fuse to the fan control module. Remember that if the fan fuse is blown – there might be a problem with the wirings or the radiator fan.

3. Faulty Coolant Temperature Sensor
There are often two different systems in different car models. Either your fan control is integrated into the engine control unit or you have a separate fan control module. In both cases, the control units use a temperature sensor to know when to start the radiator fan.

If this temperature sensor is broken, the control unit will not know when to start the radiator fan.
Some cars use separate engine coolant temperature sensors for the radiator fan and the engine control unit.
You need to check your repair manual of which temperature sensor controls the radiator fan and then resistance-measure the sensor with a multimeter to make sure it is functional.

4. Broken Wiring or Bad connection


5. Bad Connection

If the fan is not working even when the car is overheating, there might be a wiring issue or a bad connection.
Check the wirings going to the radiator fan from the control unit or relay. Check in the connector plugs for any signs of corrosion. Also, check the connector plugs at the relay and control unit.

Measuring the wirings with a multimeter is often not very effective, as you need to put a load on the wires to see if they are functional. However, as a fast test, you can check with a multimeter if there is coming power to the radiator fan.

6. Insufficient Coolant
If your coolant level is low, there is a chance that you will get air in the system, and the coolant temperature sensor will not read the coolant temperature correctly. If the coolant level is low, you need to refill the coolant to optimum levels.


Failing to do so could risk your engine becoming overheated and seized. There is no coming back from a seized engine unless you are willing to spend a lot of money.

7. Broken Radiator Fan
When your radiator fans are not coming on, it can also be caused by faulty radiator fans. The radiator fans have electrical motors inside of them, which will wear out after some years.

You can test the electrical radiator fans by taking a wire from the car battery, unplug the radiator fan connector, and put 12v+ and ground into the connector. This is the fastest and easiest way to test your radiator fans.

Category: Electric