I am new to this forum I have an 04 Chevy Suburban with the duel manual control for some reason when I put it on cold it blows hot and when it's on hot it blows cold on both sides it's working in reverse any ideas just started recently

 

I don't know if this is the answer unless actually checked.
When there is a poor ground for a circuit, the power will seek another possible path and in the process polarity gets switched and so do some functions.
This will require someone quite familiar with the system to verify

 

I'd check the electric in-dash actuators. Our 2005 Yukon had three of these.