It is probably an air vent door that is not moving. I believe your year uses elctriclal actuators so the motor may need replacement or the door may be broken. The air box is where it is located, under dash from center to blower motor.
November, 25, 2012 AT 4:48 AM
I am also giving you a walk through diagnsotic for your situation. Just use the link below to get to it;