There are vents that open and close under the dash. They allow the air to enter the vehicle as directed. Chances are there is a vacuum leak on one of them that is causing one not to open. THerefore, I would start by looking for vacuum leaks under the dask. With the engine running, you may be able to hear a hissing sound from the leak.
Let me know what you find.
Monday, November 16th, 2009 AT 8:12 AM