My trailer came up from the south and had never encountered a winter before. The old thermostat had no off switch for the furnace and would turn the furnace on with temps under 50 even if we did not want it on.
I replaced the thermostat with a Hunter model #42999, available at Lowes for $24.99. This is a non-programmable digital thermostat which will operate both AC and furnace. The key is that all of its electronics are operated off of the batteries and not the 12V
system. So even though this thermostat is for residential 24vac residential HVAC systems, we can use it on our 12 volt