Ok, replaced the one bad vacuum motor. In the process, I put a T in the vacuum line from the engine compartment to the selector valve and a vacuum gauge in the cab. I drove the Ranchero Saturday and the vacuum gauge ran 15 in Hg either at idle or driving - with the selector in the off position. Once moving the selector to any other position - vent, heat, or A/C - the vacuum went to zero! Sheeeezery. Yet another leak in that system somewhere. I wish someone made replacement electric solenoid motors and selector switch for this '75 HVAC system.
