Dealer fixed the problem saying it was the wiring "harness" to the AC unit. Unit is okay and working. Apparently, the harness is the six wire connection supplying power and communication with the thermostat. You could move the harness and ac would work. Move it again and it wouldn't. Bad connections. My explanation not necessarily what the tech said. He also said the wiring from the factory was a mess! They cut the wires and redid the harness connections. Extended warranty paid for it. So, hopefully am on to loading for our trip. Thanks for your input.
2017 Montana 3611
2012 Chevy 2500