Heater Core

Paul, do you have any movement of air when you push the different buttons?.

Mine has a central vacuum line that connects to the intake and branches off several times. One way Tees off to feed the "performance gauge" another goes to the heater /ac and branches off a few more times.

Without that central vacuum hose you won't have any movement of doors.
I have some movement like the defrost flap but no change in air flow and when i puch the a/c button the bottom flap will open and the air comes out the A/C outlet all the time