Auto Air Controller Question
 

At least I think the dad-blamed thing is called the auto air controller. It's the dial down there on the floor between the two seats.

Lemme see if I can 'splain this: The one in my car ('82 SC) rotates freely, with no resistance, between, say, 9 o'clock all the way 'round clockwise to 8 o'clock. Nearly a full turn. Then it encounters the resistance you might expect. It seems reasonable to assume that one is making actual adjustment to the system only when rotating the knob against resistance. Yes? No?

And why all this freeby rotation?

I've been getting unwanted heat in the cabin and, employing all this freeplay, rotated the knob back anticlockwise so that after encountering resistance, the dial rests at "0." 'Scuse me while I go take a ride to see if this last strategy has caused the heat to cease flowing. In the meantime, I'd be grateful for any comment anyone might care to make.

Thanks in advance.

Yeah. Mine was like that. The PO or dealer wedged a bit of paper under the dial to give some friction.
It is indeed adjusting the temp even when you feel no resistance. The resistance you feel as you get to zero is the dial hitting a switch that will finally turn the mongrel thing off. Trouble is: without friction, the dial won't stay there.
On inspection, I found that the dial was riding high on its stem. All I had to do was push the dial firmly down on its stem and the dial engage a detent arrangement that makes it click as it turns. Magic.
Hope yours is as easy.

Auto HEAT controller...