Digital thermostat mod problem
I have a Coleman Mach 8 air conditioner which I wanted to convert from manual control to a wall mounted digital thermostat for convenience, better temperature control, and to not have the fan on all the time when the compressor is not on. I ordered the factory non manual control board and the Coleman digital thermostat because it had high and low fan speed control. I watched a couple YouTube videos of similar conversions to mine.
The install went well, except I had interference from the Atwood furnace. The thermostat gets its 12 volt power supply from the furnace wires in order for the ac to work. The problem is that as soon as the ac starts drawing 12 volts the furnace tries to come on which drops the voltage to the ac, which then turns off and tries to turn back on every few seconds.
I disconnected the furnace wires, routed a separate 12 volt line to power the thermostat and now the ac is functioning properly. I suppose I will just install a separate digital thermostat for the furnace, but I don’t understand why I can’t get the one thermostat to both heat and cool as it is designed. Can anyone offer any insight?
Garland & Lou Ann