air control knobs are not switching the air from defrost to vents to floor?

[DJ]

1996 sebring convertible jx air control unit in the car that controls the air..took it to a mechanic and he told me to get a new control unit. did that and installed it and still the air only comes out of the defrost. i was told it could be a vacuum line but im having trouble finding it. could it be a fuse?

[kyle]

No, not a fuse... Its probably a Mechanical problem with the door that moves back and forth to direct the air one way or the other..

My truck did that for awhile, then mysteriously fixed itself..
The linkage on the door can get dirty and corroded over time and cause it to stick, and the vacuum is not enough to make it move..

[TexG]

It can be several causes to this.The vacuum is not getting to the control union. Means no vacuum fro the engine. Second the vacuum motor has gone bad. To repair some of these items you hap to pull the heater box out. It is a two day job if the vacuum is to the control union to get the bock out. And test the motor. The door could be stuck in the box as well. It will hap to come out to fix it. You need a vacuum pump hand to test the motor and the vacuum coming in to the control union. I would start under the hood and check the vacumm lines. If it has vacumm then it in the box or control pand. I use to do this type work on a daily basic.