why are rear vents blowing heat when front is blowing cold air? system in auto.

What is your question?

I had the system in auto ac on and in dual zone( front driver side was set to 69 and front passagener side side set to 66 , it was about 67 deg. outside. There are not controls for the rear vents. all of the front vents were blowing cold air the rear vents blowing hot air. I had to switch the system to max cooling to get the back vents to blow cold air. I only had the car a week.