The vent doors are actuated by vacuum. I would start by checking and listening for vacuum leaks nder the dash when you switch to the floor. Make sure the engine is running to create the vacuum. That way you may hear a hissing sound.
Let me know if you find a leak. If not, I will try to find you pictures of the system for you.
Sunday, December 27th, 2009 AT 8:37 PM