Recently I had my ac on and it was raining out, windows started to fog, switch
control to defrost. Cleared up, switch back to ac and now switch moves but the function doesn't. Still in defrost mode. The vehicle is 2006 chevy express.
Please help with suggestions for repair I can do myself. Thanks.

 

Just unscrew / unbolt the dash and take it apart. It's an 06 might still have a warranty on it.Save alot of time and buy the book for your van, I did and it work's wonders