I have a 2001 Lesabre. When I turn the heat or ac on the air only blows through one vent in the dash. The Defrost works and I think the floor vents work. The air blows strong through the middle vent on the passager side, and come out a little bit or none in the rest of the vents.

How do I get the air to blow through all 4 vents on the front of the dash?

Autotemp or manual?

Sounds like a blockage of some kind......

Its auto. I just move the switch from hot or cold and the switch for the fan to slow or fast