I have a 2003 Chevy Cavalier, 4 door, 2.2 L. When I turn on the blower on the upper settings, it comes over very strong on the passanger side vent, and the right-most center vent. Almost no air comes out of the left-most center vent or the one on the driver side. I havn't tried to see if the floor vents come out evenly.

Is this caused by a vent flap stuck somewhere? Would anyone know how to fix this?