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

asked by on June 18, 2016

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.

AC is not working Inspection $111.46 - $131.46 Get a Quote

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.

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


Experienced Mechanic?

Earn up to $70/hr

What others are asking

What is making the airbag light come on over and over?
If your airbag light is on then your airbag system is disabled and would not deploy if in an accident. The airbag light coming on needs a technician to scan for codes and diagnosis of the code or codes received....
Fluid leaking from transmission to engine gasket
I assume the leak you are seeing is coming from the transmission bell housing where the engine meets the transmission. If fluid is leaking from here it is most likely the front transmission pump seal where the torque convertor goes...
Car shaking at 50 MPH
Shaking at higher speeds is usually related to something that is rotating. Most of the time this will be the wheel and tire assembly. If you have tires that are worn unevenly, or if any of them have a manufacturer...
Brake exhaust doesn't shut off when I press on the accelerator.
Hello and thanks for your question. When you press the accelerator to deactivate the jake brake system, the electronic throttle sends a signal to the computer to shut off the power to the jake brakes for acceleration. The switch inside...
Oil leak coming from behind intake and transmission.
You could have a couple causes of the oil leak at back of intake manifold. (https://www.yourmechanic.com/services/oil-fluid-leak-inspection) This engine oil pressure sending unit is the most common leak in this area of the engine. Replace oil pressure sender if leaking. (https://www.yourmechanic.com/services/oil-pressure-sensor-replacement)...
What else should I do?
The fuel injectors on this engine can intermittent stick causing a misfire. The fix is to replace the injector for the cylinder having the problem. This is from a carbon build up in the injector pintle. I would recommend having...
I have a 2012 hyundai accent and the transmission shakes and rumbels in park, neutral, and reverse and sits fine in drive.
Hi there. There could be an issue within the transmission making the inside parts vibrate in neutral and under a reverse load. Also, there could be a transmission mount issue causing the transmission to shake, but when the vehicle is...
My car is overheating
If you have replaced the thermostat and radiator and the engine continues to run hot and cold and temperature is not controlled correctly. You should replace the cooling fan control switch and make sure all the air is removed from...
Why is my 2004 Honda Civic sputtering and dying after the oil was changed
Hello. This can be caused by a lot of different things. It can be from the oil issue. That could have resulted in an internal engine failure or an issue with the variable valve timing system. This system uses oil...

Related articles

The Best Used Cars to Buy For a Graduation Gift
Your Your little bundle of joy has grown up and on the cusp of entering adulthood. Graduating is a milestone, and you want to reward their hard work and show how proud you are. Buying a used car is a...
How Long Does an AC Air Filter Last?
The The AC air filter in your car (also known as the cabin filter) works to deliver clean, cool air to you and your passengers. It is usually made of cotton or paper, located under the hood or behind the...
How Long Does an AC Clutch Cycling Switch Last?
An An AC clutch cycling switch is the part of your car’s air conditioning system that engages and disengages with every cycle of your air conditioning compressor. Realistically, you probably don’t use your air conditioning every single day, unless you...