Vent defrost, actuator

[Stocktongoodrepair]

[QUOTE=Phil750;4831161]I am trying to fix the vent, defrost A/C.
1st where does these controls get vacuum from?
2nd What is the actuator? What does it do? How do you know if it's working?
My A/C is working fine except half comes out the floor heater half out the ducts. I took apart the cover to see the door. It was half open. I checked to see if there was vacuum at the actuator or the hose. Neither.
I temporarily closed the door with a small wedge. A/C comes out of vents only.
My manual does not cover this area in detail.
I'll take any and all ideas at this point.
Thanks Phil
for the 73 c10 there are 2 vacuum lines one from the t of the brake line or a t at the carb ventury port it goes to the controls and the back of the air controls/ defrost. the controls get brittle after 50 years and they are as scares as hens teeth. But if your lucky you can find a working set of controls one vac line from the controls goes to the actuator... if you buy it new thread the vent pull hook onto the actuator first rotate it 90 degrees clockwise push in past the tabs the 90 degrees counter clockwise so the tabs hold the actuator. Then run the vent hose from the center of the control to the actuator. Start the truck let it warm up. Flip the control to defros and you will hear the actuator activate and then you have air from the defrost vents...Lot of 82 to 84s have the controls that work and the actuators too... Just make sure the controls are not broken in the back. Dont yank on the vac lines that is how the controls get broken. treat the controls like a stratavereas violin that costs a million dollars becase they are delicate with a capital d. PS good luck I would add prayer to all endevors in this area.