2016 suburban furnace not firing. no sound of any kind, not working

[taylor.coyote]

Some back ground: We have been doing a combination of shore power and doondocking in weather down to 25 degrees at night while traveling the last 4 weeks. The furnace has been working well.  

During the trip we replaced our sealed AMG batteries in case new batteries  could impact the furnace function (old and died a slow death on this trip).  new batteries before setting down/hot show 13.5..... settle down to 12.7 when charged and at rest

first time we doondocked on our new batteries, we charged them using our generator. While running the the generator we used the heat strip to heat the trailer for an hour or so for the first time this trip.  All was good and we packed up and moved to our next boondocking camp.  Got set up at the new camp and turned our thermostat to furnace.... And nothing. no sound of any kind no sign of life. check and replaced the fuse....  and nothing.. no sound, no nothing...  

can anyone offer thoughts to get our furnace working?

thanks 

[dedroll]

My trailer is a 2017, I turn off the breaker for the ac and only use the furnace. I have had to turn the thermostat on and off several times on occasion to get it to fire up and if the gas ran low I would run a stove burner to help the gas flow.

[Mike and Carol]

Do you hear the click click of the furnace trying to light?  Gas flow is okay?

Are your new batteries AGMs too?  Why did you need to charge them when you arrived at your site?  When we had AGM’s they were always at or near full charge after the drive, combination of solar and truck charge.  

The furnace does not draw much from the batteries, basically just the fan.  I’m confused as to what may be going on.  Mike

[taylor.coyote]

thank you for the thoughts. gas flow is getting back to the hot water heater, I assuming also to the the furnace. Charged the batteries in the morning before hitting the road because we would be in late and did not want to run the generator  late in the new camp.

When we turn on the furnace, we get no sound at all. no clicking of the furnace trying to light. no sound at all..

[taylor.coyote]

first thing we did was check the fuse.. replaced it just in case. have lots of propane fuel and pressure

[John E Davies]

Without a volt ohm-meter (VOM) you are just drifting in the wind. You need to be able to check voltages and do some basic electrical troubleshooting. We cannot do that for you from across the country.

You cannot go wrong with this excellent one, it is perfect for RV use.

YIRU UNI-T UT210 Series True RMS Digital Clamp Meter AC/DC Voltage Tester with ohm, Capacitance Measurement

If you are not comfortable doing that, you need to hire a pro.

John Davies

Spokane WA

[taylor.coyote]

Thank you for the guidance. My electrical skills are not up to par.  I will get some help... 

thanks to all

  

[dewdev]

Obvious question. Are you sure the thermostat is set to heat and the temperature set to a higher temperature than outside?

You might want to consider buying a small electric heater to get by until the furnace is working.

[bhncb]

13 hours ago, taylor.coyote said:

Thank you for the guidance. My electrical skills are not up to par.  I will get some help... 

thanks to all

  

Before you go if it's not too late, I have a few comments and suggestions on things to try or at least narrow things down some.

1. Regarding the furnace fuse: This same 12 volt circuit powers the thermostat, directly from inside the furnace. If the thermostat display is lite up and functional,  you've eliminated the fuse as a possible source of a problem.

2. Voltage: The furnace is designed to be functional when voltage is above  a minimum of 9.5 volts. Based on your reported battery voltages, this isn't the issue and you should get some sign of life if the thermostat is calling for heat.

3. When everything is functioning normally, the first thing you should hear when the thermostat calls for heat is the furnace blower coming on, even if there is no gas getting to the furnace. Gas supply isn't in the equation, yet.

If the blower doesn't come on, the list of causes isn't long but is somewhat dependent on the specific version furnace you have. There are basically two generations of internal controls for the Suburban model installed in early LEIIs.  I'm not sure which one was being used in 2016, but the following suggestions should generally apply to either.

Turn on the thermostat and set it to Furnace mode with a Set Temperature somewhat above the current temperature inside the trailer. With your ear close to the open front air outlet on the A/C overhead, turn the thermostat off and on slowly a few times and listen for a slight click sound each time. This click sound will tell you if an attempt is being made to send the thermostat request for heat to the furnace. Note that this instruction more specifically apply to the CCC2 model thermostat I believe your trailer has. (round display with discrete buttons on the left). If it is a square CT model, you may need a second person to adjust this procedure for the fiddly touch control, one to listen while the other operates.

If the clicking isn't audible each time skip the rest of this paragraph. Otherwise, your next step will be at the furnace under the curbside bunk. Leave the thermostat On and set as before. Using a shoe or similar "tool", smack the top side corner edges of the furnace case a few times. (The term "smack"' is the technical description for and implies an abrupt force somewhere between a gentle tap and brutal pounding) The object here is to vibrate free a potentially stuck relay or switch dependent on the generation of furnace control.

If the steps above don't get positive results, you're going to need that help for some more in depth analysis and repair. If the furnace does come to life during one of the above steps however, you may still require some help to replace either: 1. The thermostat controller in the  A/C overhead.  2. The furnace blower motor time-delay relay, or air flow sail switch,  again depending on which control the furnace has.

Good luck.

 

[taylor.coyote]

bhncb and dewdev.. have been without a computer as well as heat.  just got my pc back on line. thank you for your thoughts. we are still on the road and have been relegated to camping when we can have power. we have a small oil filled heater that does a good job keep the chill away.  I'm tapped and have this repair exceeds my skills.   we are headed for the barn and will be home next week.  the trailer is already repair slot booked.

I will let everyone know what was wrong when i get it back from the shop

best to all

[Mainiac]

That is the year O II we have, and had to replace the circuit board. If I recall correctly there was a "rash" of substandard boards around at that time...

[taylor.coyote]

hope its something simple such as a circuit board. thank you for the imput

[taylor.coyote]

After all the suggestions to fix the heater... ended up having one loose wire.  John Davies had it correct .  "check the voltage..  do some basic electrical troubleshooting"