John, thanks for that. So that's why your trailer was rocking.
I've fitted a battery powered wall-mounted digital thermostat to control the furnace, and this thermostat is also able to control cooling. I assume the AC is switched by a relay, which is switched by a low current through the thermostat. If I intercept these switch wires, I assume I could lengthen them and connect them to the wall thermostat. I could pass the wires over the roof and down the refrigerator vent, or try to feed a wire between the skins to the back of thee refer, which is close to the wall thermostat. Would this work? Has anyone done this? Any advice?Thanks. Nick.