I did my o-rings a while back. Air was just coming out of the defroster vent all the time. I did find at least one bad o-ring. But when I put it back together, it still has the same problem. I went digging today and I think what I did was pulled the vacuum lines a little too hard when I was pulling the EATC out of the dash and I pulled loose something that looks like a plug with the vacuum lines going through it, with some foam around the outside of the plug as if it is supposed to be plugged into a hole. But I can't reach where it came from. I also can't even see because I can't bend my back enough. Been looking through the forums but can't find a picture of what I am talking about... I may have to go pay the dealer more money, again...