The vent doors are run by vacuum. When you accelerate, the vacuum pressure in the engine lowers. You must have a vacuum leak in the system. Check under the dash near the controler, under the hood, anywhere there are vacuum lines tied into the vent system. With the engine running, you may be able to hear a hissing sound where the leak is.
Let me know what you find.
Joe
Sunday, April 26th, 2009 AT 12:35 PM