Would be nice to know what rig and year you have, but seeing your join date, you probably have a 2012 or 2013 rig. We lost operation of our zone #2 A/C some years ago, and the thermostat seemed to be working fine, just couldn't get the A/C to work. I finally got into the control box that is located above the white ceiling assembly. It was full of corrosion that was causing the problem. I ordered a new box and installed it, and everything started working again. Not sure why there was so much corrosion, but it has been good ever since. Of course, your problem may be caused by something else, but it's not necessarily the thermostat. The photo shows the circuit board with all the crud on it.
Bob & Becky
2012 Chevy 2500HD D/A CC 4WD