Car AC fan is continuously running even when knob is at 0 means off

My Mazda 6 2007 AC is continuously throwing air inside the car even when AC is off means speed knob is at zero. When Fan speed knob is at zero it should not run. Please let me know what’s wrong

More than likely the HVAC control module is bad.



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That’s the only reason? Because that control unit is very expensive and hard to find
I mean any wiring or circuit issues?

Is the switch part of that unit? i.e. is the speed switch a separately replaceable item?

No I don’t think it’s separate

@Tester is probably right then.

I agree too. unless you have the defroster on. that will cause your compressor to stay on and blow cold air.

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Damn I am afraid that it’s not easy to find this anywhere in the market because car is old

The wind it is blowing is not cold just normal fan

Then you either live with it or junk the car

If you don’t mind the possibility of removing and reinstalling twice, you could try pulling the assembly out and spraying the switches with a plastic compatible electronics cleaner such as from CRC. If it works, great, if it doesn’t, that’s where doing the R&R twice happens.
I suspect Mazda used the same assembly over multiple years, they just might have some available, you won’t know until you ask.
Then there is eBay.
Junkyard might be another source, you might have to pull it yourself.
Lastly you could install a SPST switch on the Hotwire to the fan motor.
Me? I would ignore it, but then I can count on the fingers of one hand the number of times I have ever turned mine off.

If the air is coming through the vents while your moving, then there’s nothing wrong if your system is set to fresh. Low pressure area at the cowl will force air into the system and through the cabin. Select a comfortable temperature and let the fan run.

Yes, the auto climate system defaults to AC on when you push ON. There is a button labeled AC that you can push to shut the compressor off and just have air moving, albeit temperature controlled.

Remember, you want the AC running when you use the defroster or any time it’s humid enough to fog the windows. And be sure to set the system for fresh under those same circumstances.
Put it into recirculation mode to turn off the outside vent - preventing outside air from entering the cabin.

When the blower control module fails it can cause the blower motor to operate at high speed. If the fan is stuck on high speed, you don’t want to just live with it.

Blower motor control modules fail much more often then control panels. Replacement blower control module is $38 from Rock Auto.


Thank you for suggestion I will consider it

Its not what you are thinking as soon as I insert the keys and put it on without starting the engine AC starts working I mean air starts coming even tho fan speed knob is at 0 means fan wind shouldn’t be coming. Compressor doesn’t work until I press AC button.

Don’t some cars have the fan on (at a very low speed) anytime the engine is running?

I mentioned several times when engine is not turned on AC fan is throwing wind in the car. It should work if I turn speed knob to 1 or 2 or 3 or 4.

So you’re saying the fan speed control has no effect on the actual fan speed?

No it is working properly from 1-4. But not working when turned to 0

so, if you turn the key on but dont start the car the fan is on. if you put the speed to 1, does the speed increase or stay the same?

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