Recently I was trying to defrost my windshield but the button doesn't seem to work. The only vent that is working is the middle which aiming only at the head. The feet/windshield button doesn't seem to work and still blow through the main front vents. Any idea what could be the problem?

 

check to see if any of the blend doors are sticking, and check fuses if there are any

 

try pushing the button and holding it there for a couple of seconds..it might just be slow in interchanging...happened to my DA all the time