Why Radiator Fan Is Not Working?


The radiator fan is positioned between a car’s engine and the radiator. It’s in charge of drawing in cool air through the radiator to cool down the car engine as well as the condenser for the cabin air conditioner. Likewise, if a radiator fan fails, it’ll cause your car engine to overheat, causing decreased performance and might even damage the engine.

Your radiator fan is not working because the fan motor is damaged, there’s a problem with the wiring, the fuse is blown, the temperature sensor is damaged, there’s insufficient coolant, or the cooling fan relay has failed. To fix your radiator fan, you’ll need to solve the underlying problem.

In this article, I’ll highlight all the various reasons the radiator fan is not working. Following this, I’ve also shared solutions for each discussed problem. By the end, you should know how to troubleshoot your car’s radiator fan and get it to start working again.

6 Reasons Why Your Radiator Fan Is Not Working

The radiator fan (or fans) is intricately connected to various components to ensure it automatically turns on and cools down the car’s engine to a comfortable temperature. As such, problems with any involved components can cause the radiator fan to stop working.

Here’s a comprehensive look at the most common reasons why your radiator fan is not working.

1. The Radiator Fan Motor Is Damaged

Sometimes the cause of radiator fan failure is as straightforward as a broken-down motor. A motor breakdown can happen over time. Even the best car maintenance can only do so much to mitigate wear and tear on the engine and its parts. 

To check if the problem is with the motor, follow the given steps:

  1. Unplug the fan connectors.
  2. Take two jumper wires.
  3. Hook one wire to the positive terminal of your car battery and the other one to the negative terminal.
  4. Connect these wires to the terminals going to the fan. It doesn’t matter whether you connect it to the negative or positive terminal — it won’t harm the motor.

If the fan is spinning, the motor is fine. Whereas if it’s not spinning, the motor is likely damaged.

2. There’s Problem With the Wiring

Another common cause of radiator fan failure is damaged wires or loose connections. 

Wires going to the control unit or along the fan relay can get corroded over time. This damage can disrupt the electrical connection, preventing the fan motor from running. 

The wires can also come loose or disconnected if you recently got into an accident or bumped your car.

Read: Car Full Service Cost // Whats included?

3. The Fuse Is Blown

Your car’s radiator fan and the fan control module – just like any other electronic component — come with a fuse. The fan usually comes with a big fuse, around 50A, whereas the control module works with a smaller one.

That said, if either of the fuses gets blown, then that’ll disrupt the electrical connection to your radiator fan, causing it to stop working.

Read: Car Diagnosis Cost

4. The Temperature Sensor Is Damaged

Almost all modern cars have a temperature sensor either connected to the engine control unit or a separate fan control module. Some cars also have an engine coolant temperature sensor.

Now, whichever temperature sensor is installed in your car, its job is the same — to detect the internal temperatures and send the signal to turn on/off the radiator fan. 

Likewise, if the temperature sensor is damaged, it won’t detect when your car gets hot, and as a result, the radiator fans won’t work.

Read: Temperature Gauge High But Car Is Not Overheating

5. The Coolant Reservoir Is Running Low

Does your car use a coolant temperature sensor to operate the radiator fan? In that case, the fan might not be working because the coolant reservoir is running low.

When coolant levels get too low, air starts to build up in the reservoir which can throw off the temperature sensors. And if the sensors poorly detect temperatures, they won’t activate the radiator fans. 

Read: How Much Is an Inspection for a Car?

6. The Cooling Fan Relay Failed

Because the radiator fans on modern cars are connected to so many different contraptions (sensors, control units, switches, etc.), they need a relay to control all these circuits. 

These relays are small electromagnetic switches that can go bad over time. If that happens, the various signals required to turn on the radiator fan won’t go through, and thus it’ll stop working.

Read: How to Tell If a Relay Fuse Is Blown

6 Ways To Fix Your Radiator Fan

Now that you have an idea of why your radiator fan isn’t working let’s talk about the potential fixes.

1. Repair or Replace the Broken Fan Motor

If you find the fan motor damaged/broken, I’d advise that you take it to a car mechanic for their professional evaluation. However, if you’re something of an engineer yourself, you can check out this quick 4-min YouTube video on servicing a car radiator fan motor:

That said, in case of extensive damage, the motor needs to be replaced with a new one.

2. Fix Any Wiring Issues

The quickest way to find wiring issues is simply by looking for them. Closely follow all the wires that are coming out of the radiator fan. Check to see if there’s any visible signs or corrosion, tears, or even loose connections.

You can also try using a multimeter to check if all the wires are in working condition.

If you find any defective wiring, you should take it to a car mechanic and get them replaced with new wires.

3. Replace Any Blown Fuse

You’ll need to check your car’s manual to find out where the fuse for the radiator fan and the fan control module is located. If you see that either fuse is blown, you’ll need to replace them with a new one. 

Thankfully fuses are reasonably cheap, and you can replace them yourself.

That said, it’s important to note that fuses only blow if there’s a short circuit or electrical surge. As such, a blown radiator fan fuse can signal issues with your car’s wiring. 

4. Get a New Fan Temperature Sensor

First, check your car’s user manual or the repair manual to figure out which type of temperature sensor is installed on your car for controlling the radiator fans and where it’s located. The manual should also tell you at what rate the resistance decreases with increasing temperature.

Using this information, take a multimeter and measure the resistance of the temperature sensor. If the reading shows the same measurement as on the car manual, then the sensor is okay. But if not, the sensor is damaged, and you need to replace it.

Here’s a short 5-min YouTube video going over how to test coolant temperature sensor:

5. Refill the Coolant Reservoir

Check your car’s manual to figure out where the coolant reservoir is located. The reservoir should give you an easy view of how much coolant is inside, including markings for “full” and “low.”

Always keep coolant levels at optimum to ensure the smooth operations of the engine cooling system and the temperature sensors. 

Here’s a quick 2-min YouTube video on how to check your car’s coolant level:

6. Replace or Repair the Cooling Fan Relay

Checking whether a relay is functional or damaged can be tricky and requires some working knowledge in electronics. That said, if you like to get your hands dirty, this detailed 13-min YouTube video on “how automotive relays work and how to fix them” should help you out:

That said, relays are generally cheap, and instead of going through all the hassle of fixing one, I’d advice replacing a damaged relay with a new one.


Radiator fans can stop working because of broken fan motors, problems with the wiring, blown fuses, damaged temperature sensor, insufficient coolant, and failed fan relay.

To troubleshoot the issue, you must first pinpoint the exact problem and fix it accordingly. Potential fixes include repairing/replacing the broken fan motor, relay, temperature sensor, and wiring. You should also maintain optimal coolant levels and replace any broken fuses.

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