In the 1970's when factory A/C started to get widespread adoption in other than very expensive cars, it was common for more than one US automaker to almost standardize on a dashboard system of levers or knobs.

At the extreme was "MAX" which most people didn't realize was "recirculate" unless they read the owner's manual in those cases where it was well documented. The next notch over was "NORM" which as the name implied was intended to be the "normal" setting except under more challenging conditions. But with fresh air coming in constantly it only was passing through the refrigerant coils one time, plus sometimes the outdoor air is a lot hotter than others, so recirc is when you want the same interior air to pass through the coils more than once.

All this may go "out the window" when the exhaust fumes or worse in the outdoor air need to be excluded as much as possible.

I kind of miss the old '70's cars even though loads of them kept running long after the A/C had failed.

Regardless, I never felt alone even without a passenger, with my good buddies Max & Norm with me everywhere I went ;)