The radiator fan is a very important part of your car, and you’ve probably heard it spinning and working hard many times after driving on a hot summer day.
But if something goes wrong with the radiator fan, it can cause expensive damage to your engine if you’re not careful. That’s why it’s extra important to fix your radiator fan as soon as possible if it’s not working.
In this blog post, we will explain seven probable causes for a malfunctioning radiator fan, as well as how to fix it. We hope that this information will help you get your car back on the road safely and quickly. Let’s go!
What Can Cause A Radiator Fan To Stop Working?
The most common causes of why a radiator fan is not working are a blown fuse, a bad relay, or a broken wire. It can also be caused by a faulty coolant temp sensor, low coolant level or the fan itself can be damaged.
While these are some of the reasons, the list is not exhaustive. Here is a more detailed list of the most common causes of a radiator fan not coming on:
1. Blown Fuse
A fuse handles almost everything electrical in a car. If there is an electrical surge going toward a piece of electronic equipment, the fuse cuts off the power supply to that particular piece of equipment and saves it from destruction. This is what we call a blown fuse.
A broken fuse is no big deal, and replacing one doesn’t cost a lot of money. If your car’s radiator fan is not working, check your car’s owner’s manual and find the fuse for the radiator fan controller or the fan.
The fan itself often uses a large fuse of around 50A, while there may also be a separate small fuse for the fan control module. Remember that if the fan fuse has blown – there may be a problem with the cables or the radiator fan. Read further down in the article for diagnosis.
2. Faulty Coolant Temperature Sensor
There are two types of systems in different car models. Either your fan control is integrated into the motor control unit, or you have a separate fan control module. In both cases, the controllers use a temperature sensor to know when to start the radiator fan.
If this coolant temperature sensor is broken and won’t show the correct engine temperature, the control unit or fan 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.
READ MORE: 8 Symptoms of a Bad Coolant Temp Sensor (& Replacement Cost)
3. Insufficient Coolant
If your coolant level is low, there is a chance it is pushing air into the cooling system, and the coolant temperature sensor will not read the coolant temperature correctly. If the coolant level is low, you need to top up the coolant reservoir.
If you fail to do so, you could cause your engine to overheat, which could lead to a seized engine if you are unlucky. If your engine seizes due to overheating of coolant, it will destroy your engine and leave you with a very expensive repair cost, and is therefore something you want to be careful about.
RELATED: Low Engine Coolant Level? (Causes & Consequences)
4. Broken Radiator Fan
When your radiator fan is not working, it can actually be due to faulty radiator fans. The radiator fans have electric motors inside them that can wear out after a few years.
You can test the electric radiator fans by taking a lead from the car battery, unplugging the radiator fan connector and taking a fused 12v+ wire and ground wire into the connector. This is the fastest and easiest way to test your radiator fans. Be careful with your hands when the radiator fans start.
RELATED: 5 Symptoms of a Bad Radiator Fan (& Replacement Cost)
5. Faulty Fan Relay
Because the radiator fan often draws so much current, there is a relay that powers the radiator fan. Of course, this relay can get damaged, causing the radiator fan not to start.
The fan relay is often located in the engine compartment fuse box, but the best way is to check your repair manual to find out where it is located.
Testing a 4-pin relay is often very simple. Remove the relay and supply 12 volts to pins 30 and 85. Ground pin 86 and check for voltage coming out of pin 87. It is even better to connect pin 87 to something that draws a lot of currents, like the radiator fan, for example.
READ MORE: How to Test an Automotive Relay at Home (5 Easy Steps)
6. Bad Fan Controller Module
As discussed earlier, some cars have a separate control module specifically for the radiator fan control. This control module is often installed in the engine compartment, exposed to heat and dust. This can cause the control module to break after a while due to corrosion or other damage.
Locate the relay and check for any visual damage on the outside. You can often also open up the relay and check for any bad soldering or corrosion. Replace it if you see any problems.
7. Broken Wiring or Bad connection
If the radiator fan does not work even though your car is overheating, there may be wiring issues or a bad connection. Check the wires going to the radiator fan from the controller or relay. Check the connection plugs for signs of corrosion. Also, check the contacts on the relay and the control unit.
Measuring the wires with a multimeter is often not very effective because you have to stress test the wires to see if they work. As a quick test, however, you can check with a multimeter if power is coming to the radiator fan.
How To Fix A Radiator Fan Not Coming On
To fix a radiator fan that won’t start, you should begin by checking the fuses. You also want to make sure the coolant level is good. Then, you need to read the error codes with a scanner and measure the wires with a multimeter.
Here is more detailed information on how to fix a radiator fan that won’t start:
1. Check Fuses
The first thing you want to do when your radiator fan is not spinning is to check and replace the fuses. There will be a large fuse for the fan itself that you want to check. It will be between 30 and 50 amps, and it is usually a larger fuse located in the engine compartment. But to find the exact location of your car model, you need to check your owner’s manual.
There will also be one or smaller fuses for the radiator fan control module or relay in most car models. To find these fuses, you must again check the instruction manual for the location. These fuses can also be located inside the car.
If you find a blown fuse, you may want to inspect the wiring and try to figure out why the fuse blew. However, sometimes a blown fuse may just be a temporary problem.
RELATED: 5 Signs of a Bad Car AC Condenser Fan (& Replacement Cost)
2. Check Coolant Level
The next step you want to do is to check the coolant level. If the coolant is low, it can cause many different problems with the radiator fan.
Checking the coolant level is easy, just open the hood and locate the coolant reservoir. You will see a max sign on the reservoir and sometimes a min sign as well. Make sure the engine is cold and open the container carefully. Fill the container with antifreeze up to the maximum mark.
3. Unplug Coolant Temperature Sensor
Another way to determine if the coolant temperature sensor is the problem is to disconnect the sensor. In most car models, the radiator fan should start when the coolant temp sensor is disconnected, and the car is running.
But for this, you need to find out which of the coolant temperature sensors controls the radiator fan, as there may be a separate one for the engine control module and the radiator fan control. Also, disconnecting the engine control module coolant temperature sensor may result in a check engine light on your dash.
4. Check Trouble Codes
Modern cars use very high technology. When there is a problem, you almost always want to read the trouble codes from the control modules before doing anything else.
This is also a good idea if your radiator fan is not working. This is because in many car models, the radiator fan is controlled by the engine control module, and if your fan is not working, you’ll want to check if the ECM knows what the problem is.
For example, if the engine control module stores a trouble code on the coolant temperature sensor, it can also cause the radiator fan to malfunction. To read the fault codes, you need to use an OBD2 scanner. You can either buy one to use at home or go to an auto repair shop so they can read the codes for you.
5. Measure wirings
If you’ve tried all the things above but still can’t figure out what’s causing the radiator fan to not start, it’s time to start with some more advanced diagnostics. To find out what is wrong now, you need to use a multimeter and measure the wires with a radiator fan wiring diagram for your vehicle. This can be quite difficult if you have no knowledge of vehicle diagnostics, and you may want to skip to the next step.
Using a multimeter, you must first measure the power and ground wire coming to the radiator fan. If you have both power and ground to the fan when it starts, you need to replace the radiator fan. If you are getting no power, you need to move on to diagnosing the fan relay and find out why it won’t activate.
You can then try to bridge the radiator fan relay, and if the radiator fan starts when you do that, you know there is a problem with the relay control, like a bad coolant temperature sensor for example.
6. Talk to a professional
Fixing car problems on modern car models can be quite difficult due to all the electronics and sometimes it can be good to have a professional take a look at the car instead. Many professional mechanics have thousands of hours of training in automotive diagnostics and can quickly find problems like this.
Therefore, it doesn’t necessarily have to be more expensive to get the help of a mechanic instead of making a bad diagnosis and replacing the wrong parts all the time.
How do I know if my radiator fan fuse is bad?
The easiest and most accurate way to know if the radiator fuse is bad is to measure it with a multimeter. But in many cases, you can visually inspect it to see if the fuse wire inside it is burnt or not.
What sensor controls the radiator fan?
A coolant temperature sensor controls the radiator fan. In some car models, there is a separate CTS sensor for the radiator fan, but in most modern vehicles it is controlled by the coolant temp sensor used by the engine control unit.
How do I manually turn on my radiator fan?
There are two ways to turn on the radiator fan. On modern vehicles, you can turn it on with a diagnostic computer. On older car models, you can turn it on by bridging the radiator fan relay.
How do you fix a fan relay?
If you have a bad fan relay, it is almost always better to simply buy a new fan relay. Fan relays are often quite cheap and if you try to repair your old relay, there is a high risk that you will have the same problem in the near future.
Can I drive a car if the radiator fan is not working?
No, it is not recommended to drive without the radiator fan working. This can cause the engine to overheat, which can lead to permanent and expensive engine damage.
What happens if the radiator fan is not working?
If the radiator fan is not working, your car can overheat when the car is idling or driving at lower speeds. At higher speeds, the cooling system will still be cooled by the wind. However, an overheated engine can cause serious damage to your engine, so you don’t want to take the risk.
Conclusion
The radiator fan system is quite simple even in modern car models, and is therefore quite easy to diagnose. Often, when you have a problem with your radiator fan, it’s just something as simple as a blown fuse, a bad coolant temp sensor, or a bad relay causing it.
So now that you know the most common reasons, it’s time to start diagnosing! I hope you enjoyed this article, and with this information, you should now be able to figure out what is causing your radiator fan problems.
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25 thoughts on "Radiator Fan Not Working? 7 Common Causes & How To Fix It"
Thami
I have a corsa utility,it over heat when moving slow, the cooling fan will start very late l ve changed the the temp sensor, water pump, thermometer, radiator, l will hear water bubbling, please help
Kimberly
I have a 2008 Chevy Equinox with an overheating problem. We changed the radiator fan but it's still over heating when idle.
Magnus Sellén
I would check and diagnose the thermostat and then ensure the head gasket is not leaking!
Andrea
Hello. I have a 2013 Chevy equniox that would overheat with an idle engine or if I wasn’t driving/driving at a low speed. Took it to mechanic thinking I needed a new radiator because brother told me I had rocks and twigs in the radiator vent, I guess I am missing a radiator cover. Mechanic told me I just needed a new radiator fan, and replaced it however after replacing, mechanic told me the new fan was still not turning. After two weeks of my car just sitting while mechanic looked it over, I picked it up as they couldn’t fine the source of the problem. Car now does NOT overheat, but the air conditioning is not working at all, which was not an issue before. It just blows hot air.
Magnus Sellén
If there is a radiator cover from the factory, it can make your car overheat if it's not installed anymore. However, diagnosing a radiator fan is often a simple task for a mechanic, so I would recommend trying another mechanic if they can't find the source issue.
Richard Silva
I have a 2003 Honda CR-V. I changed the thermostat, hoses . I checked the relay on the fan and the fan works as well. But the fan still not turning on. So I’m just bypassing the relays for the fan so it won’t overheat. I’m planning to change the coolant temp sensor, do you think that would work?
Fetsi
Hi I have ford fiesta 1.4 2010 the fan is not kicking itself and water bottle is boiling and drain out all the water
lee
check all fuses and relays, coolant sensor, coolant reservoir for cracks, check cap as well, also bottom of radiator ( radiator control module ) if fan and boiling reservoir be water pump or radiator and possibly thermostat...
Lee
Done all that..still not work only when turn on ac will high speed comes on.,,everything checks out ok...even water pump.
toy
I have a 2008 Nissan march when I start my car and after driving about 5 minutes the red thermometer light comes on the dashboard for about 11 seconds and then goes of what does that mean. Is the car overheating? IT has in enough coolant and the fans are working.
Robinson
I have a 2005 Buick LeSabre I have dual fans the one on the driver side works and the one on the passenger side does not work. Trying to locate the problem. Does not overheat but notice it did not come on
Jukha
I have VW Sharan VR6 2,8 engine I can run the engine until is hot 50% or very hot and my engine will cut off and I must wait until it's cool and I can start and run again what is the problem?
Douglas lee
I have a 2007 Nissan Altima, several months ago the ac compressor clutch went out. Didnt have the money to get a new so I replaced it with a pulley. My car started to over heat, I think the coolant fans aren't work, my question is Does the ac compressor clutch control the radiator cooling fan?
James
You can have the other pulleys going in the wrong direction which will cause it to overheat. It's better to have purchased a shorter belt for the same car without air conditioner.
Ata da
Hi, it's Ayanda I m driving proton gen 2. Radiator Fan is not working and the car's temperature goes to 130, I don t know what to do
Rog
If your car is only getting to 130 F then you don't have any problem, most cars are designed to run at 180 F your car should run at about half way, or less on the dash heat gauge, so your fan normally shouldn't kick on until it gets around 180 F, or about half way up your heat gauge.
John
I have a 2000 Honda accord v6 the cooling fans wont come on even after the engine has been running for a while the relays the fuses and the fans are fine I replaced the coolant sensor switch
Robin
Hey there i just bought used peugeot 508 and have one issue with it. The fan doesn’t work when the engine is off, it only run when i turn on the engine. Could you please help me with this. Thanks
Ishmael
My Nissan np200 heater does not blowing warm or hot air i 've even changed the old thermostat and replace with new one but still the same please help.
Rog
It sounds like either low antifreeze, or possibly a bad vaccume line, that usually opens a valve, so hot antifreeze is allowed to flow flow thru heater core, in some older cars, or possibly a cable, not sure here, but thought I would throw it out there.
Routan Tongaiaba
hello I have Subaru forester 2004. The issue is with the coolant fan. it wont turn on eventhough I have replaced the temp sensor with a new one. I have checked electricity with test meter and the wiring is okay. The fan does work when you turn on the AC Can anyone help with this problem.
Nzereogu kelechi
Thanks for your writing it's encouraging am happy .In my car my car is suzuki Every bus the radiator fan fuse cuts often when ever i pass through water because our road water loged please help thanks
KES
run a 12volt wire with a switch and just turn your fan on when it is starting to get to warm or when it needs to be on
Abdul Rauf
I have Toyota camry 2014 always factory maintained. After parking the car for 15 20 minutes with ac on its engine temperature goes to half and ac trips and radiator fans are off. When switch off the car and restart all gets fine again. Please advice.
Magnus Sulwer
My problem is that the fans work when I start the vehicle but when it warms up, they no longer work! It is getting dangerous to blowing. Right now I am parked waiting for rush hour(s) to finish. Very annoying. Already replaced the fans, radiator, temp sensor and relays... I'm fitting to cut the wires and run them directly to the battery w a switch before I loose this vehicle!