Furnace Issue

[Mlemke72@gmail.com]

Looking for help with our furnace. we have a 2021 Model 3121 RL Legacy with the IN-Command system. While traveling to FL for the winter, furnace seemed to be working well until tonight. Setting up camp, started the furnace went on to other chores and sometime furnace went out. Checked breakers and fuses, all OK, plenty of propane, water heater and stove working fine. I go to turn up furnace at In Command and nothing. Fan for rear AC goes on but nothing to the furnace. Looks like IN Command is looking for an update, but don't want to update until I know everything working. Last update was a cluster >>>>.
Looking for suggestions and help. Thanks in advance.

[jsb5717]

First thing is to pull the outside cover and check the reset switch. If the furnace failed to light then the switch might have flipped off. If it's off then try the furnace again and listen to all that it does. If it works...great. If not, then what EXACTLY does it do and when does it fail.

[Mlemke72@gmail.com]

Thanks Jeff, I did pull the cover and the reset switch was not tripped. I checked all the connections internally, all good. There was some moisture in there but I think not enough to harm anything. I also checked the In Command and everything looked OK. I'm no Expert.
The Furnace does nothing! When I go to the In Command Screen. I turn on Rear HVAC to heat/gas/fan on auto. I can hear the rear Heat Pump fan turn on, but no fireup in the gas furnace.
Thanks for your help.

[jsb5717]

The next things I'd likely do is to make sure I'm getting 12v power to the control board. You could also jumper the blue wires to bypass the thermostat.

If power is present and jumping the blue wires still produces nothing then I'd suspect a bad control board.

What kind of furnace fuse do you have? Is it black (resettable) or blue (standard)? If it's black I'd replace it right away with a standard blue one. That might not cause your current issue but I'd still swap it out to eliminate that potential problem.

Also, I don't have InCommand so I don't really know how it works. Is it possible that it's sending mixed signals? Jumping the blue wires should take it out of the loop. If the furnace runs with jumped wires then we can look at the InCommand system or the relay in the AC.

[Ram Montana High Country]

I'm just thankful I don't have the IN COMMAND !!!!

[ChuckS]

The way the In Command controls the Furnace operation is via the Zone 1 roof AC control board and its gateway.

I would do a HARD RESET on the In Command system.. Doing this will let the relays inside the gateway Unlatch ( if they are hung up ) and restore furnace operation in most cases..

There are two Blue wires that go from the Zone 1 Roof AC Gateway down to the furnace control board. These are the signal wires that turn the furnace On of Off depending on Temp setting and actual inside temp at Zone 1 roof inside remote temp sensor..

I suspect your AC units are Coleman with the Rear unit being the AC/HP unit that also controls furnace operation

HARD Reset :
Turn Display Off
Turn BCM OFF
Battery power OFF
Shore power OFF
This kills all 12 vdc from batteries and converter to the roof AC control boxes and gateways that have 12 vdc ALL the Time.. even when not using HVAC..

Wait a minitute or so and then torn battery power On and then shore power .. then turn on the BCM power switch and then display switch and try HVAC again and see if furnace fires up when mode is set to Gas..

[LeftOverParts]

We’ve had rear AC or heat issues where it wouldn’t come on a couple times and found that the set point would display but the room temp was blank on the In-Command screen. A reset like ChuckS describes fixed it.

[Mlemke72@gmail.com]

Thank you,
I tried the BCM reset, I've powered down the unit, disconnected the batteries, waited for a 1/2 hour and still can't get anything on the rear AC/Heat to work. Even the room temperature is not showing anything on the screen.
It's my understanding that there is a gateway on the rear AC/heat pump that controls this. Is this statement accurate? if so where would I find this?
Thanks for all your help. I appreciate evrybodies imput.

[M&M]

The gateway is in the return side on the AC. You have to access from the roof. Remove the cover and front panel. Have a roll of foil tape to reseal. There is a diagram on the control box that shows where the furnace is connected. On my unit the wiring wasn’t correct to the furnace. It was working but I was concerned the way it was connected would lead to future problems. So I corrected it.

[Mlemke72@gmail.com]

Thanks everybody for all the help. What I finally found was that the reset at the furnace needed a hard reset It might have been stuck open. Once reset I did a hard reset on the In Command BCM, like Chuck laid out, and everything worked again. So I believe the reset stopped the Rear AC Gateway from operating correctly.
Again thanks for all the help and hopefully this little info will help someone in the future.