Skip the auto shop - Our mechanics make house calls

Symptoms of a Bad or Failing Cooling Fan Relay

cooling fan relay

Bad or Failing Cooling Fan Relay Inspection

by a top-rated mechanic at your home or office

Most modern vehicles use electric cooling fans to help pull air through the radiator so that it can keep the engine cool. Most cooling fans use electric motors that have a moderate to high current draw, and as a result are commonly controlled using relays. The cooling fan relay is the relay that controls the engine’s cooling fans. When the correct parameters are met, a temperature switch or the computer will activate the relay, which will allow power to the fans. The relay will usually be activated once it is detected that the vehicle’s temperature approaches excessively high temperatures. Usually a faulty cooling fan relay will produce a few symptoms that can alert the driver that service may be required.

HAVE SYMPTOMS OF CAR TROUBLE?
Get an $80 diagnostic
by a top-rated mechanic at your home or office.

Get a quote · Book an Appointment · Our expert mechanics come to you.

1. Engine running hot

One of the first symptoms commonly associated with a bad or failing cooling fan relay is an engine that runs hot or overheats. If you notice that your engine is running at higher temperatures than normal, that may be a sign that the relay is not functioning properly. If the relay shorts or fails, it will not be able to supply the power for the fans to operate and keep the engine running at normal temperatures. Abnormally high temperatures can also be caused by a variety of other problems so it is recommended to have the vehicle properly diagnosed to be sure of the problem.

2. Cooling fans do not function

Non-functional cooling fans are another common symptom of a potential problem with the cooling fan relay. If the relay fails, it will be unable to supply power to the fans, and as a result they will not operate. This can lead to overheating, especially when the vehicle is at a stop, where there is no forward motion by the vehicle to pass air over the radiator.

HAVE SYMPTOMS OF CAR TROUBLE?
Get your car fixed at your home or office.

Get a quote · Book an Appointment · Our expert mechanics come to you.

3. Cooling fans stay on at all times

If the cooling fans are staying on at all times, this is another (less common) symptom of a possible problem with the cooling fan relay. If the relay shorts internally, it may cause power to be permanently switched on, which will cause the fans to run at all times. Depending on the wiring setup of the vehicle, this may cause them to stay on even when the vehicle is off, which will drain the battery.

The cooling fan relay essentially functions as the switch for the engine’s cooling fans, and is therefore an important electrical component of the vehicle’s cooling system. For this reason, if you suspect that your cooling fan, or relay, may possibly be having issues, have the vehicle diagnosed by a professional technician, such as one from YourMechanic. They will be able to look over your vehicle and replace your cooling fan relay if necessary.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Still not sure about your car's issue?
Diagnose your car
What kind of issue are you experiencing?
Brakes are squeaking
Car is not starting
Car is overheating
Car is shaking (vibrating)
Fluids are leaking
Heating and A/C
Smoke or steam is coming out of the car
Warning light is on
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...


Related questions

Q: Engine overheats with new radiator, new thermostat and fan relay

It is normal for the lower hose to be significantly colder than the upper hose, but it should still be warm. The upper hose should be almost too hot to touch with bare hands, and the lower hose should be...

Q: Serpentine belt and radiator issues...

You can use regular water to flush out the old coolant and then drain the water and repeat until the water comes out as clean as when you put it in. Then refill with 50/50 coolant mix. Fir the belt...

Q: Fans aren't spinning

If the fans were working before the radiator replacement, it's possible a temperature sensor and/or wire were left disconnected or damaged. The O2 sensor should not be unplugged but may not be the cause of the fans not working. I'd...