The A/C in my 2005 suburban z71 is blowing hot air only in the front on both the drivers and passenger side. Behind the 2 front seats it blows ice cold. Does anyone know what could make this happen? I was thinking it was a blend door actuator, but shouldn’t that be either drivers side or passenger side?

 

I'd start by taking it to a good independent ASE mechanic. Front AC is controlled by an orifice tube and the rear AC by an expansion valve. A good mechanic will pull out your R134a and weigh it, and put back the correct amount.

Yes, there are several actuators controlling cool air and heat flow, and outside/recirculating air, in the dashboard.We've had these go bad in our 1994 Suburban, 2005 Yukon, 2014 Yukon - see the trend???? Shop should know how to diagnose these; oftentimes malfunctions here are accompanied by clicking noise as stripped plastic gears turn.

 

It sure sounds like a blend door issue. There are separate systems for rear and front vents in the Subarban. I had a 2003 Yukon - same layout as your 2005 Suburban - and while there is one compressor and condenser coil, there are two evaporators and separate front/rear blower and temp controls. Since the back is cooling, I doubt you have an issue with anything under the hood, making it more likely to be the blend door actuator being stuck up under the dash, leading to heat up front.