I would assume with the AC off. But whenever I turn on the heat, the car switches on the AC. I have to then shut it off manually. But I was wondering if the climate control makes efficient use of the compressor and cycles it, making it more efficient. IDK.. Any thoughts?

 

I think it is a default mode, my car does the same. If I just want the heat, I turn the AC off, if my windows are foggy, I leave the AC running, because it clears the fog much faster with the AC.

 

It likely defaults to a/c on so that the interior doesn't fog up. A/C displaces the moisture in the cabin thus, defogging the windows. Perhaps their train of thought was that if it's cold enough to need the heater, it's likely cold enough to fog the windows? Not sure.

 

Your exhale has moisture so yes, their train of thought is "THE HUMAN" will fog up the glass so the AC is use as Dehumidifier. (it used to **** me off why the AUTO turn on AC in the winter time) LOL

Also, yes it's efficient enough not to decrease your MPG much. The AC kinda on low. If you want faster defog, turn on the Defog. It will pump the AC to high and the fan to high to clear up the glass in a few seconds.

 

Cool, thanks for the input.
But if you manually shut of AC wont it automatically shut off climate control (go out of auto)? i thought it did.. I'll check at lunch time.