I have a 2004 f150 lariat. The ac suddenly stopped blowing cold air today, when it was working fine yesterday. It still blows air, just hot air. Another weird thing is that my digital temperature control on the dashboard automatically defaults to 75 degrees everytime I turn on the truck. It used to be that I would set it to a certain temperature and it would stay at that temperature when I turned the truck off and back on again. Any idea on what it could be? Thanks!