vacuum not switching at dash buttons

In my 65 barracuda the vacuum is not switching to the diff positions( defrost- heat). I verified I have 12 inches of motor vacuum going into the back of the button panel but nothing changes when I go from defrost to heat unless I move the the rods by hand. I also verified the vac diaframs work and do not leak. They will function with a hand pump using 7 inch vac. This car was once an AC car but all is removed. without removing the panel was there any AC vacuum attached to it? What is my possible issue and how to fix it.

The main thing with the AC was an added electrical switch for applying power to the clutch. First crawl under there and look at the hoses and make sure they are firmly attached to the back of the switch. Then pull the switch assy and see if it is actually moving the shuttle in the back when you push various button. This moves the vacuum routing as well making electrical connections. Look at the sticky at the top of this sub-forum for good info on how this work.