If you open the engine compartment and look, you will see a fresh air hose from the front of the car going into the computer box. At the rear of the box is a hose that goes to the cabin air intake. So long as the recirc is OFF, air is drawn in through the fresh air line, and, by default, the computer box. If the recirc is ON, no air is drawn from outside of the cabin or the computer box.

Leave the recirc OFF unless you are fighting fog on the inside of the windows and the defrost is selected. Even then, you should only use it for a minute or two.

The warmer air passing over the evaperator will keep it from icing, the water vapor will condense and drip out of the car.

I found that I NEVER need to move the dials, the ECC will try to get to the selected temperature as fast as possible. It is automatic.
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My back feels better when I sit in a Volvo seat