I just think that having the fans running at that speed all the time is not needed unless it is really hot outside. Am I wrong to think this?
No, not at all. But AC systems and coolant systems are different puppies.
There is no speed related switch in this wiring diagram.
And I am not aware of ANY AC fan control device that is based on vehicle speed. It is just not the way it is done.
I have an Alfa Romeo with AC and it seems to cycle the fans on and off when the AC is running.
It likely does cycle the fans. And the trinary switch installed in your Pantera will do the same. When the freon system pressure shows the need for greater cooling of the freon in its pass through the condenser, it will close and in turn close the relay, thus providing power to the fan (s).