Furnace Issue

[Bob Katz]

We have a 2023 Montana 3231CK 5th wheel. When we have the unit plugged in to AC the furnace will run maybe a minute or 2 and shut down prior to reaching the set temp. If I unplug or shut the breaker off the furnace will run until desired temp is achieved. I have reset the InCommand with no change in results. When the furnace shuts down the heat pump does come on. It makes me scratch my head where it don't itch. Another thing, when plugged in the furnace throughs a code of 1, which is supposed to mean something with airflow, I think this is bogus.
Thoughts appreciated.

[bobbecky]

Make sure all your heat registers in the floor are fully exposed. It's possible if there isn't enough air flow so that the thermostat inside the furnace sees temperature that is too high due to a restriction and is shutting the furnace down because of that. These RV furnaces require a minimum amount of air flow to operate correctly, and your InCommand will not have any control over that.

[Bob Katz]

Thanks for the response Becky, but the furnace runs fine as long as we are not plugged in. Furnace works fine on 12 volts only.

[jsb5717]

This is a head-scratcher. The furnace is strictly a 12v appliance as is the thermostat. So the only thing being connected to shore power would do it energize the converter, which charges the batteries. However, the converter is capable of running the coach without batteries so there is a direct connect between the converter and the 12v appliances. I’m not an electrician but I’m just wondering if the converter is outputting more voltage (or maybe less) than it should be. You might use a multimeter to check what your getting from the converter when it’s connected to shore power.

[flybouy]

I don't have In command but if IIRC that's how it works with a heat pump air conditioner. Above a certain temp the heat pump is utilized until it's too cold then it calls for the furnace. No shore power means no heat pump.

[jsb5717]

Originally Posted by flybouy

I don't have In command but if IIRC that's how it works with a heat pump air conditioner. Above a certain temp the heat pump is utilized until it's too cold then it calls for the furnace. No shore power means no heat pump.

That's a great point. I don't have In Command so I didn't even think about it. Perhaps a way to test the theory would be to connect to shore power, turn off the AC units at the inside power center breakers, then fire up the furnace to see if it runs as normal.

[ChuckS]

Did the 2023 Montana line switch away from using the MicroAir thermostat units and adapt HVAC control via In Command?

The 2022 and earlier units are using Coleman roof A/C units with Dometic Atwood furnace.. all are controlled via MicroAir thermostats..

[Bob Katz]

I believe the thermostat control is now through the InCommand as there is no external thermostat anywhere in the 5th. It is an Atwood furnace, heat pump I believe is also Dometic. But is is worth trying by shutting down heat pump breaker and see what happens. My assumption is it would be similar to removing the plug from the ac. Will let you know.

[RJS3791RD]

FWIW..... I think they made the transition to In Command sometime in 2022. I have a 2022 Montana Legacy (late production) and all AC and Heat controls are through In Command

[JRTJH]

Does your trailer have the optional "Legacy Package" ????

In-Command is not "standard equipment" on the Montana line. All Montana fifth wheels come "standard" with conventional switches, thermostat and remote control, even the current 2023 models (according to the Keystone website)

The In-Command is "optional equipment" and is a part of the "Legacy Package" which also includes the following:

Legacy Edition Package
+ $4,500
Dexter® Gladiator™ axles w/drum brakes
Winegard® GW-1000 Gateway 4G LTE WiFi Router
Surge protector
Furrion® S-Vision™ cameras with 7" monitor (side & rear view)
iN-Command® Pro with Global Connect™
Electric power cord reel
Built-in surge protector
Rear fiberglass cap (N/A on 3761FL, 3763BP, 3791RD)

So, without knowing if you have the Legacy Package, which is an extra cost option on A FEW Montana fifth wheels, but not all of them, it's hard to know exactly how to troubleshoot.

You said that there's no "separate thermostat" which means you probably have the Legacy Package and In-Command, but, it's also a remote possibility that you just overlooked the thermostat...... Not saying you did miss seeing the thermostat, but .......

[Bob Katz]

JRTJH - Definitely the Legacy package. As per JSB1757 suggestion I tripped the 3 AC breakers and had the same results, furnace starts up, fires up and runs for about 1.5 minutes and shuts down. Only time I can get furnace to run full cycles is when I disconnect from ac and run on battery.

[jsb5717]

In glancing through the In Command manual in looks like you can select Gas only for heat. Is yours set to Gas or Auto? Have you tried just Gas?

[Bob Katz]

JSB5717 - same results. Definitely something misconfigured in the InCommand and/or converter.

[jsb5717]

I see there are are several steps to properly set up the In Command for your specific layout. Has that all been done correctly? Have you tried a system reset? You might also call their technical support number.

[Bob Katz]

Thanks all for your input and help, unit is now at the dealer to figure out and get fixed. I will post the fix when the dealer/keystone corrects the problem.