Radiator Fan Not Working – How Do You Get It Running Again?

Radiator Fan Not Working – How Do You Get It Running Again?

So, you are driving on the road at a low speed, and you notice how the temperature gauge is slowly climbing up and your car starts to overheat. You probably wonder why is this happening to you. You are sure that everything is in check, and the last thing on your mind is that your radiator fan not working.

This can be a bummer. Fans are there for a purpose, and that is to turn on when there is a reason for it. And that reason is to cool down your radiator (to learn more, check out our guide on how long does it take for a car to cool down). The radiator fan not working may cause your engine to overheat, especially if this happens during a hot summer day.

Summer can be really harsh on cars. The cooling system is saving your car from overheating during the whole summer. The most important piece of the cooling system is the fans. I’m saying this because when everything becomes boiling hot in your engine.

Your car can’t keep up cooling itself with the drag of warm air. Your car sees the danger when the temperatures are rising, and turns on the radiator fan. This fan will then drive some extra cold air into the radiator. This basically saves your engine and also your wallet.

If your engine overheats, things can get pretty expensive. A new engine can cost thousands of dollars and the installation is a significant hassle. So, keep this in mind.

If the radiator fan has stopped working, follow along. Because we have some explaining to do on why this annoyance is happening to you right now. And trust me, there are plenty of reasons why the radiator fan not working.

Radiator Fan

The radiator fan works in a simple way. It engages when it sees that the cooling system cannot handle the heat. This heat is usually caused by hot conditions or uphill climbing, putting a lot of load on the engine. This makes the water pump spin a lot faster and will move the water through the engine very quickly.

And unfortunately, in these situations, there isn’t enough cool air to make the cooling possible. The radiator that is placed up front behind the grill, doesn’t get enough cool air to continue working properly and keep the car at the right temperature. Here the cooling fan comes into place.

The cooling fan spins at high speed, delivering cool air to the radiator in the process. This cool air cools the radiator down and reduces the temperature in the engine. Resulting in better performance and the engine avoids being overheated.

This fan has saved your engine’s life numerous times. If it’s not for this radiator fan, your engine will probably overheat in these types of situations. So, it is a smart idea to keep your radiator in check and always keep track of the temperature gauge. Especially if you are driving uphill and your engine is put on a high load.

If your radiator fan not working, you may get in big trouble and your engine may overheat. So be aware and always remember, if you see that your car is overheating, better come to a stop, and let it cool down for a few minutes. Because you never know what may happen.

Radiator Fan Not Working Symptoms

Overheating is the only symptom that you will instantly notice. You will see how the temperature gauge starts to climb into the red zone.

This is a clear sign that your fan is not working, or something else is wrong with your cooling system. You need to stop the car if you notice that it starts to overheat.

Don’t touch the coolant cap, because it may splash you with hot coolant and burn your skin. Leave it like that to cool off, and continue driving. After you come home, make an appointment with your local mechanic.

Or if you are into mechanical stuff, you can test your radiator fan by yourself. And in the next chapter, we are going to explain how you can perform this check.

How To Check If Radiator Fan Is Working

Here are some quick ways to check if your car’s radiator fan is working…

1. Crank Up the A/C

Radiator Fan Not Working

A simple way to check if the radiator fan is working is to start your engine and turn the air-conditioning system (A/C) to the maximum speed. If the fan is spinning, then it means that the fan motor, fuse, wiring, and relay are all working properly.

The only drawback of this test is that it isn’t showing you, if the coolant temperature sensor, temperature switch, and ECU are powering the fan when the temperatures get boiling hot.

In some cars that run with variable fan speed. The ECU is taking a lot of input from many different sensors when deciding on how fast and how often it should run the fan. If some of these inputs are faulty, they will send the wrong data to the PCM. Then the PCM will give wrong instructions to the fan on when should turn and at what speed.

In this case, you should check your sensors and see if they are working properly. If some of these sensors are failing, you will also see a check engine light on your dash. This light means that is time to troubleshoot.

2. Scan The Car For Codes

Connect your OBD scanner tool to your port and scan the car for possible errors through a car code scan. If these sensors are bad, you will get some errors. The tool is going to tell you precisely which sensors are bad and how to replace them. Usually, two sensors are connected to this issue, the coolant temperature sensor, and the temperature switch.

If you want to check at what temperature the fan turns on. You will need to turn the AC off and run your engine until it reaches a normal working temperature. Most of the fans turn on when the coolant reaches around 200 degrees.

In this case, if the fan does not turn on it means that its something wrong with your fan circuit. You should perform resistance checks with an ohmmeter and see if the fan circuit is any good.

3. Test The Fan Motor

You can also check the fan motor with jumper wires. To perform this task, just unplug the wiring connector that goes to the fan and use the jumper wires that will take juice directly from the battery, and then power up the fan.

If the fan motor is good then it should run at normal speed when you will supply it with 12 volts of power. If the bearings are noisy and some bad sound is heard from the fan, or if the fan runs slow, then this is a clear indicator of a worn-out motor. In this case, you will need to replace the fan assembly with a new one.

Why Did My Fan Stop Working

There are plenty of reasons why your radiator isn’t working. We are going to list them all with their proper fixes. And we also are going to give you some troubleshooting bits of advice on how you can get these things done at home on the driveway (fun fact, go check out our guide on how to clean oil off driveway). Without doing all the work at a workshop and spending a lot of money on labor in the process. So, follow along while we dive into this problem.

Causes #1. Bad Wiring

When troubleshooting this issue, it is important to inspect the wiring that goes to your radiator fan. Be sure that all of the wirings are okay and aren’t messed up.

There are many factors that can ruin the wiring of your radiator fan, like age, heat, and rodents. Yes, rodents can eat up your wires and cause some electrical issues like fires in the worst-case scenario. So, it can be handy to learn how to keep mice out of your car.

So, if you park your car in a place where there are rats or mice, it is a smart idea to check the wires. Also, heat can be a great factor when it comes to wires and can melt them down.

If you want to check your wires, just unplug the electrical connectors for the radiator fan. Check the wires with a voltmeter and see how much electricity they are transmitting. If they are transmitting 12 volts.

It means that everything is in proper working order. If there is less, then it means that the wires need to get checked if there is any damage to them and replace them if needed.

If the wires are okay, then you can also inspect the relay. The relay is providing the wires with electricity. This relay can wear out with age and cause these issues. So, give it a check with the voltmeter as well.

If the relay is bad then you need to properly replace it with a new working relay that will feed your radiator fan with electricity with no issues whatsoever.

Causes #2. Broken Thermostat

Thermostats are known to go bad and cause all sorts of cooling issues. They can die all of a sudden. Especially a newly replaced thermostat that you don’t expect to cause you major issues.

A thermostat is an important tool that your car uses to be properly cooled. The thermostat opens and closes when there is a need to. How it works is simple. When the temperatures outside are cold the thermostat stays closed and the coolant stays in the engine. When the coolant reaches the working temperature the thermostat opens and the coolant circulates through the cooling system.

If this thermostat doesn’t open when the engine reaches the working temperature, the coolant will stay inside the engine block and the engine will start to overheat. This will result in the radiator fan not working. The ECU will decide that there is no need to turn on the radiator fan because the thermostat is closed and the radiator is most likely below the cooling temperature.

After you notice this issue your temperature gauge will probably start to rise and some overheating issues will appear. The engine will start to feel ill and will eventually die. If there is too much heat it may cause cracking of the block, or it may cause the engine heads to warp.

This will happen to you if you do not replace the thermostat when you see an issue. When your engine overheats there is something wrong. Test your radiator fan like we described above and also check if your thermostat opens and closes when it needs to. This will help make you sure, that it’s the thermostat and you can properly replace it.

When it’s time to replace the thermostat, it is a good idea to go for a brand that is proven and will not let you down. You may do this work by yourself or you may take your car to the local mechanic’s shop. If you are into DIY, swapping the thermostat and the water pump by yourself is an easy task.

Causes #3. Broken Fuse

A blown fuse is probably one of the most common reasons why your radiator fan isn’t working as it should. Fuses are created to blow, in order to prevent some catastrophic engine damage caused by a bad electrical installation. Sometimes they blow by accident, you never know what may happen.

In order to check the fuses, open up your hood, and there you will find your fuse box. Find the fuse that is right for the radiator fan. Pull it out and give it a look. If the metal wire inside is still connected it means that the fuse is ok. If the metal inside is burnt, or there isn’t a connection between the two connectors then it’s time to replace the fuse.

Fuses are relatively cheap and you can find them in your local parts store. Replace the fuse with a new one and you are ready to go. Simple as that. If you are still getting a check engine light on the dash, it is time to delete the codes with an OBD scanner tool or an auto code scanner. If the fuse blows soon after, then it is maybe something else that is causing this issue.

Radiator Fan Not Working

Causes #4. Broken Coolant Temperature Sensor

A broken coolant temperature sensor can also make the radiator fan not work as well. When this sensor fails it may cause overheating in the process. This sensor may also relate to other different symptoms as well. Some of them can be really damaging for your engines like poor fuel economy, black smoke, uneven work of the engine, and check engine light.

How this sensor works is pretty simple. The sensor measures the temperature of the coolant and sends this data to the ECU. Then the ECU based on this data decides on what will be the next steps, should it turn the radiator fan on or not?

When this sensor breaks can cause a permanent cold or hot signal. This signal will make your engine think that it doesn’t need extra cooling to be applied from the fans, and it will cause the radiator fan not to turn on when it has to. And this may lead to overheating.

Causes #5. Coolant Level

Check your coolant level. If you are running your car on low coolant, it may cause the radiator fan to work all the time and fail prematurely. The radiator fan is not meant to work all the time, so keep this in mind.

Fill up your car with coolant and you will be good to go. And always track your coolant level. Make sure that it is always below the max and above the minimum.

Causes #6. Broken Fan Clutch Or Fan Belt

Fan clutches and belts are also known to break. These two are important pieces of the puzzle when it comes to cooling. The clutch is connected to the engine and makes the fan work when needed.

If the clutch is broken the fan won’t spin. This is usually the case on old V8 pushrod engines. So, if you have one. I think you might want to look at this clutch and its belt and see if they properly work.

Causes #7. Bad Radiator Fan Motor

If nothing works, then it’s time to see if the radiator fan motor is okay and is properly spinning. You can check this by plugging a different power source into your radiator fan.

Unplug the connector that feeds power to the radiator fan and connect it to a battery. If the fan spins, then the fan is ok. If it doesn’t spin, or it spins with a lot of issues, then the problem is probably the fan motor that is inside.

You can fix this issue by replacing the old radiator fan with a new one and your radiator fan should work properly and turn on when needed.

Causes #8. Damaged Fan Blades

Damaged fan blades can also cause the radiator fan to not work properly. The blades of the fan are essential for creating a flow of air that cools the radiator. If the blades are damaged or bent, they may not be able to create enough airflow to cool the radiator, leading to overheating.

Check the blades of the radiator fan for any visible damage. If the blades are bent or damaged, they need to be replaced. It is always a good idea to replace the entire fan assembly instead of just the blades, as there could be other underlying issues with the fan motor or other components.

Causes #9. Obstructions in the Fan

Sometimes, debris like leaves, plastic bags, or other foreign objects can get stuck in the fan, preventing it from spinning. This is more common in vehicles that are often parked outside or in areas with a lot of debris.

Inspect the fan for any obstructions and remove them if found. Make sure to also clean the surrounding area of the radiator and the fan shroud to prevent any future obstructions.

Causes #10. Faulty Fan Relay

The fan relay is a switch that controls the power supply to the radiator fan. If the relay is faulty, it will not supply power to the fan, and the fan will not turn on. The relay can wear out over time or get damaged due to heat or electrical issues.

To check the relay, you can swap it with another relay of the same type in your vehicle. If the fan starts working, then the original relay is faulty and needs to be replaced.

Causes #11. Defective ECU

The Engine Control Unit (ECU) is the computer that controls various functions of your vehicle, including the radiator fan. If the ECU is defective, it may not send the signal to turn on the fan, leading to overheating.

Diagnosing a faulty ECU can be complicated and usually requires professional equipment and expertise. If you suspect that the ECU may be the issue, it is best to consult a professional mechanic or take your vehicle to a dealership for further diagnosis.

Causes #12. Malfunctioning Fan Switch

The fan switch is a sensor that turns the fan on and off based on the coolant temperature. If the switch is malfunctioning, it may not turn the fan on when the coolant temperature rises, leading to overheating.

To check the fan switch, you can bypass it by connecting the two wires that go to the switch. If the fan turns on, then the switch is faulty and needs to be replaced.

Causes #13. Wiring Harness Damage

Apart from the wiring connected directly to the fan, the wiring harness that connects various components of the cooling system can also get damaged. The wiring harness can get damaged due to heat, age, or rodents chewing on the wires.

Inspect the wiring harness for any visible damages like cuts, burns, or chewed wires. If any damage is found, the wiring harness needs to be repaired or replaced.

Causes #14. Corroded Electrical Connections

Corrosion on the electrical connections can also cause the radiator fan to not work. Corrosion can occur due to moisture, and it can prevent electrical current from flowing through the connections.

Check all the electrical connections related to the radiator fan for any signs of corrosion. Clean the connections with a wire brush and apply dielectric grease to prevent future corrosion.

Causes #15. Inadequate Coolant Mixture

The coolant mixture in your vehicle should be a 50/50 mix of water and antifreeze. If the mixture is not correct, it can cause the engine to overheat and the radiator fan to work harder than necessary.

Check the coolant mixture in your vehicle and adjust it if necessary. A hydrometer can be used to check the specific gravity of the coolant and determine the mixture.

In conclusion, there are many potential reasons why your radiator fan may not be working. From bad wiring, a broken thermostat, a blown fuse, a faulty coolant temperature sensor, low coolant levels, a broken fan clutch or fan belt, a bad radiator fan motor, damaged fan blades, obstructions in the fan, a faulty fan relay, a defective ECU, a malfunctioning fan switch, a damaged wiring harness, corroded electrical connections, to an inadequate coolant mixture.

It is important to diagnose and fix the issue as soon as possible to prevent engine damage due to overheating. If you are not comfortable diagnosing or fixing the issue yourself, it is always recommended to consult a professional mechanic or take your vehicle to a dealership for further diagnosis and repair.

Can You Drive With A Broken Radiator Fan

Yes, you can drive your car. But in order to keep it safe, you shouldn’t run it too hard. Be gentle on the gas pedal. Because your car is not in perfect condition. A little push on the gas may cause the temperature level to climb and possibly overheat the engine. Also, it is not recommended to drive your car uphill if you have a radiator fan not working problem.

Don’t drive your car for too long like this. Make an appointment at your local mechanic in time, or if you are into cars, you can replace them by yourself.

Radiator Fan Not Working

Radiator Fan Replacement Cost

The cost of a radiator fan replacement may vary. Depending on what you are replacing. For example, if you are only replacing the fan that is broken, it may cost you $200 to $400. Also, your mechanic will charge you for the labor. Depending on how many hours are needed to get this job properly done.

If you want to swap the fan by yourself, then you will only pay for the fan. But if your fan is broken it’s probably because of the fan motor. This job will cost a little more money to be done properly.

Around $600 to be more exact. Not counting the money needed for the labor. With that money you pay for the mechanic, it adds up quickly! In the end, it may cost you around $900 for the whole job.

But be brave and try something new. Especially simple things like radiators and fans, that can be swapped with no previous mechanical knowledge needed. The only thing you need is a will and a little bit of research online on how the job is done.

Aftermarket Radiator Fan

You may also go a step forward and go aftermarket. Especially if you are running an old classic motor. Look for the best solutions and swap your whole cooling system. Systems back in the day were junk compared with new ones.

You can get a proper one for less than $600. If you mount it by yourself, even better. But keep in mind to be careful, because these radiators and fans are known to be very prone to damage.

Facts: Common Reasons Why This Problem Appears

  • The radiator and cooling system are vital in keeping your vehicle from overheating, and a malfunctioning radiator fan can cause serious problems, including engine fires.
  • A radiator fan is necessary when the vehicle is at low speeds because the wind doesn’t push through the radiator, and it cools the coolant down to prevent overheating.
  • Modern cars have a light to indicate when the engine is overheating, and a yellow or red light might be a sign of a malfunctioning radiator fan.
  • A blown fuse, a bad relay, a broken wire, or a faulty coolant temperature sensor are common reasons for a malfunctioning radiator fan.
  • If the radiator fan’s fuse is blown, changing it is inexpensive, and the user manual can help locate the fuse for the radiator fan.
  • The temperature sensor is used to determine when to start the fan, and a faulty one can cause the control unit to malfunction.
  • Low coolant levels cause the engine to overheat, and repairing a seized engine can be expensive.
  • The electrical motor of the radiator fan can wear out after regular use, and if all other factors have been checked, it may be the cause of a malfunctioning radiator fan.
  • The fan relay, an electromagnetic switch that controls the power supply to the cooling fan, can get damaged over time and cause the radiator fan to malfunction.
  • The radiator fan’s control module in the engine bay is susceptible to heat and dust, causing corrosion and eventually failing.

Radiator Fan Not Working: In Conclusion…

In this article, we discussed everything you need to know when you are having an issue with the radiator fan not working. We shared all of the symptoms related to this and their proper fixes.

If you have a radiator fan not working, then it’s time to make an appointment with your mechanic to see what’s the matter with it. You may pay a lot of money but in the long run, you will save even more. Imagine if your engine overheats and blows up. You don’t want that thing to happen to you.

If you run a classic, it is also a good idea to see the aftermarket offering and get a modern cooling system. It will be a lot better than those old systems that were made back in the day.

Frequently Asked Questions (FAQs)

If you’re still curious about the radiator fan not working, our FAQs here might help…

How Does A Car Radiator Work

As your engine continues to run, it’ll naturally create and emit a lot of heat. To counter this, a car’s cooling system’s first line of defense is the thermostat. A vehicle’s thermostat is designed to detect if there’s too much heat. If that’s the case, it’ll permit and release coolant to flow from the radiator and have them circulate around your engine to try and cool it down. As the coolant flows around, it’ll absorb excess heat from the engine, before circulating back to the radiator. The coolant then flows through the radiator’s many small channels and passageways. Here, a heat exchange occurs, as cooling air rushing in from the atmosphere absorbs heat from the coolant. This coolant is now chilled and will flow back into the engine to continue absorbing more heat.

How To Tell If A Fan Clutch Is Bad

If your car’s fan clutch has gone awry, there are several ways to tell. For starters, your engine tends to run a bit hotter than usual or would outright overheat, especially when you’re cruising at lower speeds or are idling. This is because the fan’s clutch fails to engage the fans themselves, thus failing to force air through the radiator. In addition, another common symptom of a faulty fan clutch is having the engine run too cold. During wintertime, a bad fan clutch might run constantly (instead of intermittently), hence cooling the engine a bit too much. Besides that, you might notice how the radiator fans emit a lot of noise and vibration. So much so, that it could even force the fan blades to flex and shatter over time.

Should Radiator Fan Turn On When Ac Is On

In short, yes. A car’s radiator fan should always start spinning once you’ve turned on the air conditioning unit. This is necessary, as your car’s AC unit is reliant on the radiator fans working for its heat exchange process. Basically, it forces air to flow over the AC condenser, getting rid of excess heat away from the condenser. This allows your AC core to cool down, enabling you to enjoy cold air from the cabin. If the radiator fans didn’t spin, the AC unit would remain warm, instead. In some cars, the AC unit’s condenser unit might feature a dedicated fan, separate from the radiator fan. Oftentimes, the radiator fan turns on once the AC compressor is circulating refrigerant/freon throughout your car’s A/C system.

What Makes A Car Run Hot

There are many reasons why your car is running hot or is outright overheating. Usually, the blame lies with your car’s cooling system. For example, if the thermostat failed, it wouldn’t be able to actuate and permit coolant to flow through and cool down your engine. Elsewhere, a bad water pump might also cause your car to heat up excessively. It functions to circulate coolant around the engine, so if the pump fails, no coolant is able to flow. Speaking of, contaminated coolant, low coolant levels, or even excess air bubbles in the coolant flow would disrupt its ability to absorb heat from the engine. Just as much, leaky or bad radiator hoses, a faulty radiator, or a radiator fan not working, would all impair the cooling system’s ability to cool down a hot engine, too.

What Happens If Your Radiator Fan Stops Working

The radiator fan is a vital component of your car’s cooling system. It won’t make much of a difference when you’re moving at speed, as air rushing past your car would be able to handily exchange heat with the hot coolant in the radiator. But, what if your car is stationary or is traveling at lower speeds? In these instances, the radiator fan would normally kick in and start spinning to force air to pass through the radiator, thus initiating the heat exchange process. If the radiator fan were to stop working, it may be hard to notice at first. But as you keep on driving, you’ll quickly notice rising temperatures. If you don’t stop and let the engine cool down, it might even overheat, as the hot coolant in the radiator isn’t given a chance to release any excess heat.


  1. Oscar Vazquez

    Thank you for the information it was very helpful.

    1. Harry Gibson
      Zack Norman

      Thanks for the comment, Oscar Vazquez!

      Cheers, glad that our guide here has been of some help 🙂


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