A/C on high or low fan speed for best cooling

I keep hearing people say that your hot car will cool faster (and it’s often over 100F ambient here in Texas)if you set the A/C fan on low. With recirculate (which admittedly is not total) it would seem that this is wrong. Ignoring chill factor from the blowing air, the total BTU transfer should still be better with the fan on a higher speed. Yes, a low speed will produce cooler air out the vent, but less of it, and less total cooling.

For quickest cooling - select recirculate and max fan speed.

To cool my car fast, I open the windows and set the fan on max, fresh air setting (NOT recirculate). Why? Because the inside of the car is likely to be much hotter than the outside. (It gets over a hundred regularly where I live, too). Then when the car cools down, I close the windows and set on recirculate. And yes, the cooler I want the car, the higher the fan setting.

It takes much more energy from the AC to remove the moisture from the fresh air than it would to just cool the hotter air inside the car. This is why automatic climate controls switch to recirculate when the car is very hot.

As Tardis wrote, recirc is generally best, but if the outside RH is lower than, oh, 30% you might be better off with outside air. To give a little more detail about fan speed, a low fan speed will cool the (cabin) air more slowly, but remove humidity faster. At a high fan speed you can end up with cool, clammy-feeling air. If you recirculate hot, dry cabin air, OTOH, it is not a problem.

Think about it this way, it takes as much energy to remove a given volume of water from air as it takes to boil it out of a pan on the stove. Get that vivid picture?