HVAC Blend Door issues. Control head or actuators?

[Xavier]

Recently picked up an SS and have been giving it some TLC. The most recent issue I've been working on is the AC wasn't working when I got the truck. Turns out the refrigerant was low in addition to there being an issue with the HVAC controls or actuators.

I don't seem to have any control over the hot/cold actuator (top in middle of dash), driver, or passenger actuators. The recirc actuator does change position correctly but it sounds like it is constantly running towards either extreme, open or closed.

The hot/cold actuator will cycle from one side to the other at key on but then will stick to one extreme, which happens to be full heat. It also stays pushing that direction.

The driver and passenger actuators seem to just stick to one extreme and don't move anywhere else, unless an actuator is plugged in that's not at that extreme yet. They also seem to stay "running" to that side.

I have a second control head which doesn't seem to make any difference as well as two spare actuators of unknown working state. They don't change the result no matter what position they are out in.

Looking for some advice from others who have been down this road.