Why is my car AC stuck on Bi-level settings?

Question

My 1990 Lumina AC is stuck on Bi-level settings. When I change to AC or Max it still comes out as if it is on Bi-level. I know it is Bi-level settings because the air is coming out of the bottom and not too much the top vents. It worked fine yesterday. Why is this or what can be the possible causes?

Answer 1

The air diverter is stuck.

Answer 2

THE TRAP DOOR IN YOUR AIR DUCT SYSTEM IS NOT MOVING COULD BE ELECTRICAL BUT I BELEAVE IT IS VACUME ACTUATED AND IT IS MOST LIKELY THE VACUME COMING IN TO THE CAR FROM UNDER THE HOOD OR THE VACUME AT THE CONTROL IT IS MADE OF A PLASTIC AND GETS OLD AND BREAKS EASILT IF BENT WHEN DOING OTHER REPAIRS

Answer 3

sounds like a mode door actuator or mode door problem . Kind of hard to walk you through it online sorry