My blend door resets itself every once and a while. I will lose cold air for a few seconds, hear a thump then cold air returns. This is on my 07 F150 with auto climate control. I do have the updated actuator.

Anyone?

 

Anyone?

 

OK I think it has something to do with coming to a stop and taking off again, the door always seems to clunk when I do that.

 

It sounds like you probably have a vacuum leak somewhere. When you open the throttle vacuum pressure always drops. When you let off the throttle it always increases.
The most likely place for the leak is where the little vacuum line goes through the firewall right behind the battery. The fumes the battery gives off always decay that hose first. If the leak isn't there, just keep searching the vacuum lines until you find it.

 

It is a 07 I am having trouble with, all the AC blend, mode doors are electronic and not controlled off vacuum now.

 

I didn't consider that, but have read it before. I have no experience with those. But it is odd, that it is the exact same symptoms. That's another thing that makes me go Hmmm!

 

Bump

 

Bump

 

Bump anyone?

 

There is a TSB in regards for a grinding noise when air flow changes. I do not know if that would work for you but the TSB number is 08-8-9.

 

Yes I have read that one and applied fix, not the problem I am talking about though with the random thumping from the ac system upon acceleration.

 

Bump. I think now it could be the air inlet door, but i still dont know.