My air condition is blowing half the dash cold air and half the dash like the heater is on any ideas?

 

if it has auto air,it could be any of a vast number of things....manual air,its most likely a temp actuator

 

My truck does this all the time and most of the time i just have to turn it off and restart the truck. But some times i have to disconnect the neg. terminal and reconnect.

 

I also have a 04 z71 and had this problem when i got it. I took it in (still under warranty) and they finally found it had a bad temp actuator, I believe they said. It was blowing cold air out of all vents besides the passenger vent by the door was blowing all hot air. Got it fixed and now it freezes me out!!