Go to page 5-122 of your owners manual and read about the Auto Defogging System.
My Elantra had dual temperature controls so the driver and passenger could select their own temperature. The car would blow A/C air even if the A/C button was off. I disabled this function to stop that cold air from blowing out of the vents.
I live in Florida now so my A/C is always on in my Tucson.