A car cooling fan or radiator fan plays an important part in keeping your engine cool by blowing air through the radiator. It turns on when the engine gets too warm, especially when the car isn’t moving.
Some of the most common causes of a faulty radiator fan include a blown fuse, a faulty temperature sensor or a defective fan relay. If the fan stops working, your engine could overheat and be damaged.
Below, we’ll explain how you can tell if your cooling fan isn’t working and what you can do about it.
How does a car’s cooling fan, or radiator fan work?
If you’ve ever wondered what a car radiator fan does, here’s a simple explanation. When driving, air flows through the radiator to keep the engine cool.
If you stop, like in a traffic jam, an electric cooling fan forces air through the radiator to prevent overheating. This fan, usually located near the radiator, activates when the engine is stationary or getting too hot, triggered by the coolant temperature sensor.
Overheating is a common cause of breakdowns, so it’s important to keep your cooling fan in good condition.
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How do I know if the car radiator fan isn’t working?
Many modern cars don't have a temperature gauge, but there'll be a light to tell you if the engine's overheating.
If a red or yellow temperature icon lights up on your dashboard, you should stop as soon as it’s safe to do so. You might also see a warning message on the dashboard display.
A yellow light probably means that the coolant level is low. A red light means that your engine's overheating.
What happens if the radiator fan stops working?
If your radiator fan stops working, your engine can overheat, leading to serious damage and might even cause your car to stop completely. In the worst case, this could happen on a motorway and result in a collision.
Always take your car to a garage or consult a professional if you suspect a problem.
What are the signs of radiator problems?
Some common signs that your radiator is having problems are:
- Your engine overheats
- The warning lights on the dashboard come on
- Visible coolant leaks
- Steam coming from under the bonnet
How do I know if the car radiator fan isn’t working?
Many modern cars don't have a temperature gauge, but there'll be a light to tell you if the engine's overheating.
If a red or yellow temperature icon lights up on your dashboard, you should stop as soon as it’s safe to do so. You might also see a warning message on the dashboard display.
A yellow light probably means that the coolant level is low. A red light means that your engine's overheating.
Here are some other signs something isn't right with the fan.
Car fan comes on after a short journey
It’s not always a problem when your car fan comes on after a short journey, as it may just be due to exceptionally hot weather outside. However, this can also indicate a problem with the cooling system – your car may be low on coolant or there may be a malfunction with the electrical systems (like the relay or a short circuit in the fan).
Your car fan coming on after a short journey could also be due to you keeping your air conditioning running. In any case, it’s best to get your car checked over by a mechanic.
Cooling fan comes on when the car is cold
If your car’s cooling fan comes on when it’s cold, this could be a result of the cooling system’s thermostat being stuck in a closed position, a problem with the cooling fan relay, or a damaged temperature sensor.
Cooling fan is very loud
If you can hear your car’s cooling fan and it’s much louder than usual, this could be due to several reasons:
- There’s a build-up of debris within your fan (dust etc.)
- The blades of the fan are bent or damaged, causing them to catch on other pieces of the cooling system
- The bearings are worn out or the rotating assemblies are unbalanced
- You can see radiator fluid leaking underneath the car
- The radiator is making a hissing noise
- The radiator looks rusty
- The coolant level has dropped rapidly
- Your car is hot but the radiator is cool (do not check this yourself, as there’s a risk of getting burnt)
- Pull over as soon as it’s safe to do so
- Turn the engine off
- Get your car checked by a garage or contact us for help
- The engine overheating warning light comes on (this looks like a red or yellow temperature symbol)
- You can see steam coming out from under the bonnet of your car, or a leak from underneath your car
- Your car's temperature gauge is reading much higher than usual, especially when stuck in traffic
Why is my car's cooling fan not working anymore?
In most cases, a problem with your cooling fan can be fairly serious, so it’s best not to chance it – always get your car checked over.
Your mechanic will look for one of these common cooling fan faults:
Blown fuse
As the radiator fan is electrical, the problem could be with the fuse.
Your car’s manual should show where the fuse for the cooling system is. If the fuse has blown, the mechanic will need to replace it and check the operation of the fan right away.
Car radiator leak
If you have a car radiator leak, your car radiator sealant may have failed or peeled away entirely in places, causing the all-important coolant to leak out. Signs that you have a radiator leak include:
Faulty temperature sensor
On most modern cars, the cooling fan is controlled by the Engine Control Unit (ECU) which gets a signal from the coolant temperature sensor.
If it’s not working, the fan won’t turn on when it needs to, which means the engine might overheat.
Defective fan relay
The fan relay controls the power to the cooling fan (and the cooling fan relay switch). If there’s an issue with the relay, the fan will be affected.
It may cause the fan to cut in and out, or not come on at all.
A wiring issue
Faulty car wiring could be to blame. The mechanic will check to see if all the wires to the fan are properly connected and in working order.
Something wrong with the fan motor
If the motor that drives the fan is faulty, then a new motor will have to be fitted.
Coolant level low
Check the engine coolant level. If your engine coolant’s too low, it means that the cooling fan will have to work harder to keep the engine at a normal temperature.
To check the level, look for the coolant expansion tank in the engine bay. There are usually two marks on it – a minimum and maximum level mark. The coolant level should always be between these 2 marks.
What do I do if my radiator fan breaks?
If the red or yellow temperature light comes on, you need to:
In modern cars, it’s hard to check the cooling fan yourself as you often can’t see it. And if it has stopped working, you’ll need a professional to repair it for you.
How do I fix my car fan that’s not working?
Unless you’re a fully trained mechanic or run your own garage, you shouldn’t try to fix a faulty car fan yourself. Get it checked by a professional. Attempting to fix a faulty car fan by yourself may result in mistakes, leading to even bigger problems with your vehicle. In the worst case scenario, it could also result in personal injury.
It may be off-putting to think about the cost of getting it fixed professionally, especially if you don’t have a breakdown cover, but it’ll be worth it in the long run.
Replacing your fan
How do I know when my car radiator fan needs replacing?
There are a few obvious ways to tell if your car’s radiator fan needs replacing:
How much does it cost to replace a cooling fan?
If you're getting a cooling fan replaced and you don't have Parts and Garage Cover, the one-off price at a garage could range anywhere from £100 to £500+ depending on the scale of the problem.
Find out how breakdown cover can help you if you have car trouble: