72 heater/defroster function

[Gary S.]

The car in question is a 72 without a/c. I just repaired my clock and after re-assembling my center cluster and console, I may have run into a bit of problem. The "air/def" thumbwheel on the left of the control unit blows anytime the fan is on. The owner's manual states "When this control is in the "OFF" position, the system is totally inoperative." In addition, there is not a noticable difference between defrost and air when I rotate the thumbwheel. I believe that the thumbwheel controls the air/def function by vacuum with the round mulit-connector on the side of the control unit. How does this also shut off the air (if it does this function at all) when the fan switch is on? Can anyone shed light on a good place to start looking? This car passed its ops check twice during Flight judging so I know it worked. I also know that I had half the dash and cluster apart so it can be anywhere. I just don't know where to start looking for either a connector loose, the vacuum connector loose, or anywhere else.

Any ideas, guys and gals?

Thanks, as always.
Gary

[Gary S.]

Never mind! Duhhh!

So I say to myself: "Self, you idiot, if this is a vacuum controlled setup, how you gonna test when the engine is off?"

Needless, to say, when vacuum is applied to vacuum controlled switches, they work much better. It works fine with the engine running. It has been a long day.

Gary