Scottie's answer is good -- this one's better...
Set temp setting to hottest, turn the vent(s) to def/heat. (That's upper and lower). Adjust to ventilate OUTSIDE air, that's the arrow coming in. Turn on the a/c button. Crack the passenger side window an inch. Activate the rear defrost (if applicable). Adjust heat setting as necessary for comfort, but the windows will be pristine ! Promise.