AC blowing hot air when off?
 

I had the main board replaced on my AC a few years ago. Lately, I noticed that when I turn the system off, it blows hot air through the vents. I have to turn it down to 60F, THEN turn it off to prevent this from happening. It never did this prior to the AC work. Thoughts?

Re: AC blowing hot air when off?
 

Blend door actuator. Its what regulates the hot/cold air.

Re: AC blowing hot air when off?
 

So I did some google on the blend door actuator....my system is running fine when it's on - keeps cold and hot no problem. The hot air only comes out when the system is turned OFF. If the actuator was bad, wouldn't the AC not run normally?

Re: AC blowing hot air when off?
 

What are you calling "system"?? The entire hvac or just the ac unit?

Re: AC blowing hot air when off?
 

I guess the AC. Because if it blew hot air when the heat was on, then that wouldn't be a problem then, right? :)

Re: AC blowing hot air when off?
 

Hopefully it's not the Blend door actuator ... I just replaced mine what a PAIN IN THE ARSE!!! It drove me NUTZ and cut my hands up!! It's a 10 on the SUCK Scale!!!

Re: AC blowing hot air when off?
 

I dont suppose you have your hvac system on auto climate control when this happens do you? If so your inside air temp sensor reading may be causing your problem. It will default to -40c if its not working and try to heat up the cab

Re: AC blowing hot air when off?
 

It's always on auto - interesting! So how would I test if it's the sensor or the actuator?

Re: AC blowing hot air when off?
 

Mine has always done this...whatever my last HVAC setting was (temperature and output vent), once I turn it off it still blows; just a little bit. Every other aspect of the HVAC seems to work fine...

I simply got in the habit of changing the output vent to the defroster before shutting it off.

Re: AC blowing hot air when off?
 

mine does the same thing when turned off, it seems like the vent kicks open and lets the hot air through the vents. I don't think you can turn on recirc without the system on?

Re: AC blowing hot air when off?
 

Well, glad to see it's a common problem. It's not worth me paying out of pocket for at the dealership, that's for sure. I'm going to start trying the defrost setting trick, that sounds like a really good solution.