Skip the auto shop - Our mechanics make house calls

Q: AC/heater fan runs constantly even with switch off

asked by on

Lost fan speed control and fan keeps blowing even with the switch off. AC still works but AC fan keeps blowing

My car has 138000 miles.
My car has an automatic transmission.

The most common cause of this problem is the blower motor control processor mounted in the A/C evaporator case. I’d start by checking that first I were you. I you need some assistance however, feel free to contact a professional mechanic who can diagnose your A/C system firsthand and make the necessary repairs.

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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: Would a blown coolant hose, at heater core, cause loss of power?

Yes, severe overheating will cause loss of engine power and also has a high potential to damage the engine as the pistons scuff the cylinder walls and the exhaust valves stick in the valve guides. If the overheating is severe...

Q: What should I do if I have to leave my car for a long period of time?

If your vehicle is going to go more than two weeks without being driven, then you should run the air conditioner before leaving it. Turn your car on, leave it idling, and turn the air conditioner on its highest setting...

Q: How much do you charge for a water pump and clutch fan

Hello, thank you for writing in. The water pump is a very common place to develop leaks. Leaks in that area are a good indication. You can check the hoses and their connections to make sure they are secure and...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
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...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...