2001 coleman mach thermostat

[workdogruss]

Greeting all,
My question relates to the Coleman Mach TrueAir theromstat on my 2001 Winnibago Adventure.
Is it detrimental to the ac/heat unit to operate only the lower switch for electric heat and leave the upper switch in the neutral/off postion?
I do not want my Gas Heat to come on when I ask the Electric Heat to activate. Any setting I program that asks for more than a 3 degree increase in heat will activate the gas function of the heater even though I set it to electric heat. I understand that particular function is built in and normal because of the request for a temperature being in excess of 3 degrees.
The issue is I don't carry propane on my RV. Consequently, the fan portion of the "gas" heater just pumps cold air through the floor vents while the electric heater is trying to heat the RV through the overhead vents.
Having removed the faceplate on the thermostat, I find that the control switches themselves are tied together by means of the switch cover as shown in the second picture, and operate simultaneously rather than independently when moving the switch to various positions. Speaking strictly of heater settings, can I assume the top switch is operating the propane option and the lower switch is operating the electric option?
My intent is to manually leave the top "propane" switch in the "off" position and activate only the lower switch which appears to be the electric aspect.
Here's the thing. I don't keep propane on the RV so I've no use for the Gas Heat option, but it tries to run when i move the switch as designed with the two tied together and set all the way over to Electric Heat.
Any thoughts would be much appreciated.

[Old-Biscuit]

Operate with cover off and try different positions on the switches to verify which is GAS and which is ELECTRIC

Having the GAS switch turned OFF should have no detrimental effect on thermostat/system functions
*I do believe top switch is for GAS function

[workdogruss]

Thank you Sir. Having experimented a bit today, I too believe the top switch to be 'gas'. As well, I appreciate your thoughts regarding detriment to thermostat/systems.
Best Regards, Russ

[Mudfrog]

Taking out the switch will probably work. If not, I would think you could either disconnect the thermostat wire that feeds the furnace or remove 12 volt power at the furnace itself.

[David 70]

I had my thermostat quit on me last summer. I removed it trying to figure out why. If I remember there is a plug with three wires in the wiring in the wall that goes to the furnace. Perhaps just unplugging it will take the furnace offline. I know it won't work with it unplugged but there is a relay in the hvac unit that also controls the furnace. Hopefully the heat pump will still work without the furnace.

[Old-Biscuit]

Coleman Mach True Air Thermostat manual
Pg 8 -9 wire diagrams
https://www.manualslib.com/manual/16...?page=8#manual


Gas heat low......White wire
Gas heat high.....Orange/White wire
*Wires are soldered to t-stat circuit board and pin connectors inside wall

Turn the switch off and be done with gas heat
*easiest method and reversable

[Mudfrog]

Originally Posted by Old-Biscuit

Coleman Mach True Air Thermostat manual
Pg 8 -9 wire diagrams
https://www.manualslib.com/manual/16...?page=8#manual


Gas heat low......White wire
Gas heat high.....Orange/White wire
*Wires are soldered to t-stat circuit board and pin connectors inside wall

Turn the switch off and be done with gas heat
*easiest method and reversable

The switches in the image show to move together via the molded piece of plastic the OP is holding between his fingers. Wouldn't he have to cut that piece of plastic in half so that it wouldn't move the upper switch?

As far as soldered into the stat, I'd simply cut the wire, leaving enough where I could splice it back together later if needed.

Or wait,, maybe you're talking about the rocker switch mounted on the furnace. Turning it off should work.

[Old-Biscuit]

Furnace maintenance switch ON the furnace...turn it off and no DC to furnace BUT it may interrupt DC to thermostat which is needed for A/C Functions.


Cutting the molded piece for thermostat and turn the #1 switch off to stop GAS Heat

[workdogruss]

Outstanding information from all of you. Thank you very much. I'm going to resolve this issue at the thermostat switch. Found some cooked wires today for the #2 condenser. I'm guessing I've only been running on the #1 unit for who knows how long. That would explain why the a/c and heater never really do a lot of good. This forum with it's amazing archives and members have given me what I believe to be a fair understanding of how to address that issue. I'll surely let you all know how that progresses....regardless of good or bad. Thanks again to all.