We had just the opposite problem where the unit wouldn't go into the heat mode. If it is operating normally in the Electric Heat Mode, i.e. thermostat displays Electric Heat and it's truly pumping warmed air (not room temperature air) but won't switch to the cooling when in the AC mode it's likely there's a problem with the control board.
The control board is supposed to activate a switching valve to designate whether to blow cool air (AC mode) or warm air (electric heat mode) into the living area. If it works fine in one mode, but won't switch to the other the control board is likely not getting the proper signal to the switching valve.
I called the Coleman Service and support phone number and spoke with a technician:
https://www.airxcel.com/coleman-mach/contact-usHe directed me through a diagnostic process that included checking for a signal at the switching valve when the thermostat was in the Electric Heat Mode. In our case there was no signal at the valve which meant the control board had failed. He sent me a new board at no charge.
Our problem arose when the unit was only 14 months old. A new board at that time cost around $240.00. The technician felt it was a premature failure and covered it under warranty. If you decide to go this route be sure to have the unit model and serial number when you call. While he didn't say so I believe there was a series of units that had an inordinate number of control board failures. If your unit falls within the serial number range they may warranty the part as a courtesy.
Hikerdogs
2013 Winnebago Adventurer
