On our trip back from Maryland a couple of weeks ago, I got the E1 error message on the Dometic CCC 2 thermostat (loss of communication with system control boards). When I did the reset it didn't work and the display showed Zone 4 (I only have 2 zones). Needed heat so I called a mobile repairman, after messing around for about an hour he ran 2 wires out from the furnace thermostat connection and I went to Walmart to get a cheap thermostat just to enable the furnace to run.
Got home and let it alone for awhile, on a whim I did the reset procedure on the thermostat and low and behold zones 1 & 2 showed up. Returned the thermo. wires to their correct connection and the furnace works fine.
Now after all that I'm wondering if the heat pump and ACs will work, Is there a safe way to test them with only 20 AMP power available (without getting on the roof)? Maybe just adjust the thermostat to start them and turn it off immediately when hearing the start up hum?