I plan to get the '00 Max into the shop, but wondering if there's something simple I can check and possibly take care of myself...

Last Thursday morning, I ran an errand, and the A/C was working just fine. Later in the morning, I headed out, and the A/C was not cooling at all, and it's continued the same ever since. What would make it stop cooling out of the blue like that? If I put it on 'auto' and crank it down to 65, the fan turns up, so it seems like it's sensing the internal temp OK. It just went from perfectly cool to what seems like just acting like a 'vent setting' in a single drive.

I am hearing no out of the ordinary noises, and there have been no puddles under the car or anything.

Any ideas what might cause such a sudden change?