No ac system is installed. Not necessary in my neck of the woods.
What you´re saying makes sense, but why would the cold air not come out of random outlets instead of the fixed order (bottom right, top right, then left side, then defroster, right to left) that it does now? And why does turning the heater off and back on restore hot air (for a minute or so)?

The control panel is sliding levers, if that makes any difference.

c