Chevrolet Repair: 2003 Chevy Suburban A/C Problem, 2003 chevy suburban, chevy suburban

Question
The front a/c blows hot air and the rear blows cool air.  It will start off blowing cool and then eventually begins to blow hot air.  I have replaced the front dash unit thinking it was a bad switch.  The air comes out like it is stuck on high heat, not just heat from the engine. I had the freon level checked and it was a little low, but nothing to worry about.  Any ideas?  My check engine light came on about the same time and I have yet to find some to tell me what it could be.  Just guesses.
Thanks for your help!

Answer
Hi Cully, There is a switch on the accumulator/dryer called a low pressure cycling switch. This switch goes bad often. If the compressor is running then this isn't your problem!! I would have to say maybe you have a problem with your mode door actuator. I have replaced a couple of these too. This actuator moves the temp door in the dash.

Hope this helps

Mark