2018 GMC 2500 - I haven’t driven the truck in two weeks. Got in this morning and the AC was blowing hot air in the full “Auto” setting at 67 degs. Adjusted it down to “Lo” and no change. Put it in manual mode, front vent and high fan speed and it was so cold it fogged up the windows. Any ideas? Dealer had no clue and said they haven’t had that issue before. Thanks in advance.