73 Barracuda, factory AC car.

I have just rebuilt the HVAC box, tested all of the actuators, inspected and pressure tested the control tubes (using mouth vacuum/pressure) and charged the AC.

The AC functions and I get cold air if I have the temp switch in just the right place (I assume it is a spot where the valve is actually closed on both sides) so I know the system is working.

My box, however, is not functioning properly. I have checked the plumbing to the source line through the firewall and can move the heat/def door with the switch set to def and a vacuum pump. The door will also return when I go to heat. However, the fresh air door won't actuate in either direction, nor will the heat/AC door, which is currently stuck on AC. I was obsessively careful to photograph the box pre-disassembly and use numbered tape strips to identify the tube and its actuator. For the moment, I'm assuming the integrity of that part of the system.

I'd like to rule out my control switch, as it has visible electrical damage at the 12V connection from before I owned the car (of course the bulkhead connector also has damage at the ammeter wire. That said, the switch works electrically, in that it kicks the a/c compressor on appropriately (Max AC, AC and DEF).

Is there a method to test the vacuum switching of the HVAC Control Switch? I'd like to confirm its integrity before pulling the dash apart (again).

Also, any other suggestions?

Thanks
Chris