When I turn the dial to defroster setting I still get air coming out the dash vents. Are these controls vacuum operated? Where should I start looking first?

i'm having the same problem with my 03 dakota, a/c doesn't blow out the vents driver side driver side heated mirror went bad (hardly ever use it, still went bad) had to rebuild rear axle twice once under warranty, went bad 50K later then i rebuilt it myself. Now why would i want to buy another Dodge