What causes your 1996 Dodge Ram to redirect the AC air when you accelerate?

Answer

Vacuum...the doors are most likely(but not always) controlled by vacuum, and a vacuum leak in the vacuum reservoir or lines could be the cause...for detailed diagnosis...You should be able to find a shop manual at your local library with diagnostics and specs -- make copies of the right sections as they are usually only available in the REFERENCE section...good luck :)

First try replacing the check valve that is in the main vacuum line. This is usually the problem.