Skip the auto shop - Our mechanics make house calls

Q: Radiator fan not working when a/c is on.

asked by on

Hello. Car does not overheats, cause I notice the fan running when car is at operating temperature, but when I turn a/c at cold setting, fan doesn't run. It's supposed to run when the a/c clutch is engaged. A/C system was checked and is fully charged and cabin gets cold when car is moving, but at traffic, or when car is stopped, air starts to blow warmer. I imagine the same fan has 2 speeds, but I need a way to troubleshoot the failure. I'm going to chek the relay today, but some people tell me this car has a control module for the fan operation? Don't want to damage parts, and the dealer is too far awai from me. Thanks in advance for any reply.

My car has 33000 miles.
My car has a manual transmission.

A: Your vehicle fan is controlled by two diffe...

Your vehicle fan is controlled by two different relays in the engine compartment fuse box. One is for low speed and the other is for high speed. The ECM controls both of the relays. The wires to the cooling fan motor are black (ground) brown (high speed) green with white stripe (low speed). With the engine running and the A/C turned on, check for power getting to the low or high power wires to the cooling fan motor.

If you do not have power to the low power wire, then try to replace the relay first. You may be able to temporarily swap the high and low speed relays to test to see if fan is coming on with A/C on. If it does, then try and replace both relays since they may both be burnt. If you find you are getting power to the cooling fan motor but it is not turning, then you have a defective motor. If you do not have power and the relay swap did not work, then you will need to have the computer checked to see if its able to turn on and off the fan using a dealer scanner. The problem is most likely the relay or fan motor.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car Overheating

If your coolant level was really low and you added coolant you could have air trapped in the system that creates a block to normal circulation. There are little weep holes set high in the coolant "piping" that allow you...

Q: Where is the cylinder head over protection sensor located in 2015 ecoboost mustang

Hello. From what you describe it would appear that the sensor you are referring to would be the coolant temperature sensor, also known as the engine temperature sensor. As it's name implies, the coolant temperature sensor monitors the coolant temperature...

Q: What should I do if I need to get towed?

While your car is designed to last for a long time, many issues could result in the need to have it towed. Of course, you need to make sure that your car is being towed correctly in order to prevent...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
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...