A/C Blows Hot and Cold Air

I hand the same problem, i had hot air in front and cold in the back. remove the black plastic cover located right below your dash, covering the climate air vents .Locate the . . . I think the part name is call the Modedooractuator.This piece is made of plastic and had a electric connector attach. Well , I remove it and notice this vent door inside this part was not fully close so I clean it. , I spray a little lubricate and re-install it, Its been about 4 years and I never had that problem since. You may want to Google this" Moderdooractator"