mine did that when the compressor was going out. but only lasted like a week. then the bearings started squeeling and burnin up.

 

The temp door is controlled by an electronic servo motor. Not vacuum. I would have a close look at your temp selector, (which I assume is just a variable resistor?) and see what it looks like, and verify it works as it should. I am going to guess..... that is doesn't.

Might just be a loose connection.

And why are you resurrecting a year old thread?