In my 19H I took out the original heat thermostat, and installed a coleman thermostat that runs both the heat and the AC. It took rewiring the AC unit and disconnecting the AC thermostat in the AC unit itself, and using a couple of relays, but it works GREAT! Now the fans turn off when the AC turns off, which I wanted, I have better control of the actual temperature in the camper. Plus the heat is also on the same thermostat, so that's an added benefit. I used it all spring and summer without a problem.
Model X19H Expandable
GMC Sierra Pick up
Been a camper since I was a kid, and that was a long time ago :)
From pup tents with no floors, to tents with floors and flies, to a pop up, to the expandable.