There is also an a/c bypass door that if open will do same thing, it has to be the opposite or closed to work. So, two doors there. That a/c one is exposed when the glovebox is opened then fully dropped to dump its' contents on the floor. Look at blower and the small slits in box there, the slits should have the door behind them blocking the slits from passing air, if the slits open up into deeper area the door is still open and needs shutting. The shaft to that one is known for stripping to not work, you can make a hook out of coat hanger to reach inside slot to pull door back down closed.