In this case, you are most likely looking for a vacuum leak. The vent doors that direct the air are actuated by vacuum. Check under the dash for leaks, damaged hoses, or disconnected hoses to the system. NOTE: With the engine running, you may actually be able to hear a hissing sound where the leak is coming from.
Let me know what you find or if you have other questions.
Monday, December 28th, 2009 AT 3:05 PM