Hi everyone. First post here. I've got a 2002 F-250 gas burner, and I flipped the air to defrost the other morning and the air kept blowing from the panel vents. Everything else works fine with the A/C. All the other positions work, the floor vent positions work, but every time I try to switch it to defrost the air keeps blowing from the dash panel vents. Any ideas? Could it be the Blend Door Actuator?

Adam

 

welcome to FTE.
sure sounds like the blend door is not working.

 

No, the blend door and the BDA only controls temperature.


For whatever reason, the Panel/Defrost door is not moving when it's supposed to. It's spring-loaded so it's supposed to go to the DEFROST position if its vacuum motor looses either its vacuum supply or the actuator gets disconnected.

Since yours isn't moving, you've got either the door mechanically binding, something fell down the defroster outlet and jammed it, or the vacuum supply is not switching properly from the control panel and vacuum is remaining supplied to the motor on the port that causes it to hold the door in the PANEL position.

Simplest thing to do is reach under there and disconnect the red hose and see if the airflow reverts to the defroster. That will tell you which route to pursue. As best I recall this motor is back behind the glovebox, you'll probably have to flip the door downward for access.

 

Thanks y'all. I drove my truck to work today with it set on defrost and just let the air blow through the panel vents and after a while I heard a fluttering noise that sounded kind of like fan blades hitting something for a second and the defrost finally kicked on. It takes a minute or so but it will switch over to defrost now so I don't think it's jammed. Someone else told me it might be the vent mode actuator, and that cam might be turning slow to move the door. I can't find where that part is located on my truck though.