Unsure if this is the right spot or not. But I'm having problems with my vents, air only comes out of the defroster and foot panels. From what I've read it means there's a vacuum leak. But I've done the smoke technique where you blow smoke into all of your hoses and search for smoke to come out of the leak but I haven't found anything. And on the hvac panel it self I can see the circular device moving to switch panels. And I've felt all my hoses a.d haven't found a crack, am I missing something?

 

I think your cable that operates the door to switch air paths is either broken or unhooked from the door. I am not totally familiar with all the parts, but I know it's in the dash and of course hard to get to.

 

So I'm going to have to take the dash apart?

 

First take the trim off from around the control head and see where the cables go. I think they go back and to the passenger side where the heater box is. You might be able to access it from the passenger side floor board. Like I said, not totally familiar with it, but have helped my son with a similar problem on his GMC P/U.