Hey TGO, my issue with my HVAC mode selection is that it always blows on the floor in addition to the mode selected, from what I can see, the top door does not move depending on the mode selected, thus it is always sent to the floor.
(This is an 88 GTA with the digital HVAC buttons).
Defrost = Defrost & Foot
Heater = Foot
Vent = Vent and Foot
Bi-Lev = Vent and Foot
AC Norm = Vent and Foot
AC Max = Vent and Foot



I can physically push the top door open by hand, so I know it is not jammed or stuck shut - but you can feel the resistance keeping it shut.

 

I came across this picture, it looks like I need to access the upper mode door? Is this correct?

 

So I've got an update and may honestly leave it this way - I personally never use Bi-Level and only use Heat for my feet when it's cold out.
After jumping around a couple threads I tested something.
I disconnected the RED line (which controls UPPER MODE DOOR) ((the door that wouldn't open for me))
And for testing I connected the BROWN line (which controls LOWER MODE DOOR) to the Red.

To my surprise it works! and on top of that apparently when the upper is opened, it pulls the lower as well.

For some reason the RED line was not producing any suction at all... so something with the line is messed up or the actual Digital Dash motor thing in the passenger's foot well.




-- Here is behind the dash, viewed from driver's foot well, you can see the RED line that connects to it.




-- As I mentioned I connected the BROWN line to it, and it opens both.

Hope this helps someone in the future.

 

on my 90, that door is controlled by a cable. but its not digital like yours. when you pull the lower lever, I think it controls that door. I forget now, but that is what I recall. if someone is pulling their condenser for any reason, now is the time to get in there and clean up that door area. and give it a little lubricant. and make sure it closes completely, otherwise when your a/c is running, you'll get hot engine air mixing.