On Mon, 15 Aug 2016 15:46:02 -0700 (PDT), "Ron D."
wrote:

in one of my vehicles (circa 1982) that I put the AC in the car from a "box of parts", so I know that system intimately.

There was a switch that was set when the temp was set to "recirculate".

The outside air was "partially" controlled by the "AC module". 1/2 of the recirculate damper was controlled by the AC module. To prevent freezing of the evaporator, the module would open up 1/2 the damper to outside air. If that didn't work, it could shut off the compressor.

But the compressor never got shut off, and the AC is fully charged and
not subject to freezing, and most importantly I can run in any of
those 3 speeds for a long time and nothing changes.

Idle typically increases when the AC is turned on.

But the idle doesn't change speed by changing the AC fan speed.

Even with the fan off, you get "flow thru ventilation" in non-recirculate mode. So, the temperature was still modulated by how far the "water valve" was open. Not all cars have a water valve, but many have a way to turn the water off to the core under MAX cold.

Toyota doesn't call it max, and the fan wasn't on the high speed, but
the outside air vent was closed.

On Friday, August 12, 2016 at 2:51:36 PM UTC-4, Micky wrote:

Latest car has climate control.