IT sounds like you have a vacuum leak. The vent doors are actuated by vacuum from the engine. If there isn't enough due to a broken, damaged, or disconnected hose, the vent doors won't open and close properly.
Check under the dash for leaks and throught the firewall where the vacuum source comes from, the engine. Sometimes, with the engine running, you can hear a hissing sound coming from a leak.
Let me know what you find.
Tuesday, September 22nd, 2009 AT 10:29 PM