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AC acting weird, any ideas?

So today my AC started acting weird. I was out driving (I am in Florida) and i had the AC cranked up to full blast as usual however we were having a thunderstorm so the windows started to fog a bit so I switched over to the heater just for a second to get any fog off the windows BUT when I switched the dial back over to cool, the heater kept on running. I wasn’t sure what I have done but I can’t seem to get the car to spit out any cool air. Thinking maybe it just needed to rest I finished my errands and on the way home still heat. However I left the car to idle when I went to get the mail out of the mailbox and when I came back the car was nice and cold again, so I did a test and drove around the block as as soon as the engine started to rev up as I was driving heat started to come out again. I checked the radiator nothing going on there, car temp was in the middle the entire time (and just had the thermostat for the engine replaced a few months ago) Anyone have any ideas? Its an 02 Nissan Sentra. 130,000 miles.

First, I understand your dilemma. Those designers up north just do not understand a southern rainstorm. Cars in the south need a windshield/dash vent position. But I do have to ask why you didn’t use the defrost position and add just a little heat if needed? The defrost uses the AC to dry the air aimed at the windshield.

This option would be great on cars in the north too. Designers just seem to think they know what drivers need better than drivers do.

Anyway, to the problem at hand:

"car temp was in the middle the entire time"
If the temp dial was in the middle and it stopped providing cold air, it sounds like the AC system stopped functioning and all you were getting was heat from the heater core. It could be the compressor failed, loss of refrigerant (a leak), icing of the expansion valve, or some other component failure. I’m afraid this one will have to go to an AC guy with the expertise and equipment to properly diagnose the cause. Sorry I can’t be of more help.

On one car I had the ac would shut down if I ran through a deep puddle. Maybe that happened here.
And I’m guessing it was the outside of your windows fogging up?