Whoa... have you never driven any other car before?
Its totally normal that the air gets muggy after turning off the air conditioning. When the A/C is on, moisture is pulled out of the air on its way into the car (cold air can't hold as much water as warm air). When you turn off the A/C, any water that has condensed on the core that hasn't dripped out of the car (look under any car when its A/C has been on a while - it drips water) will get put back into the air that is blowing into the cabin.
Solutions include not turning the on in the first place or never turning it off... or just living with the muggy air for about two minutes while it dries out the core.
-Charlie