Is that a cable or vacuum controlled door switching A/C+=heating sustem? Check a repair manual to see which kind ... or if you move levers to change where air comes out, then maybe door is binding or cable is loose. If it is a vacuum controlled system, could be vacuum switch... move lever and listen to see if door moves in relationship to it or not or if instead you get a hissing sound. I think the vacuum control unit moves through s much smaller arc than does the cable unit. If it is not a cable or vacuum switch or leaking vacuum tube leak, it could be a ruptured diaphram on one of the vacuum actuators/motors. Again, checking the repair manual for your year and model should let you see how difficult it is to get to the components in question. (so you can determine if you want to attack it or take it to a professional. Before diving into it, however, FIRST check the trouble shooting/trouble isolating sequence in the appropriate repair manual to narrow down the possibilities and maybe even pinpoint the faulty item as well as the fix. Note that manuals are available on this site! for a nominal cost. (or if your local public libs has manuals, check them.)

Answered by buickman2
1 question asked