OK, I have an 04 fx4 screw with the 5.4. When I turn on the air it comes out through the defrost and vents and floor instead of just the vents. What could this be?

 

I'm pretty sure they are supposed to, but really minimally, not to match what is coming out of the vents or even close.

 

Sounds like you have a bad blend door actuator. This is an electric motor that moves the door, a panel that pushes air in one direction or the other.

If you're not under warranty any more, it's not that tought to fix. The actuator is behind the glove box, and it you pull the radio and drop the glove box forward you have all sorts of room to work.

 

The blend door and its actuator have absolutely nothing to do with the airflow destination. It is only used for temperature blending, that's why it's called a "blend" door.


Steve