Front furnace in 378XL won't run

[CaptainJustice]

Fan starts in response to thermostat setting, never gets any heat, then fan shuts down within about 15 seconds. Can turn off, wait, and replicate.

Rear furnace working just fine so it's not a general propane delivery problem. I'm on the road and it's cold! Anyone with ideas?

[JBP]

It still can be a flow problem. It seems that my valve was not opening all of the way so if the hot water heater was running there was low flow to the furnace. I had to make sure everything was off and then it would light (most of the time). I took it to the FR dealer in KC and he discovered the problem. It was a cold Christmas and a constant worry that something would freeze. I decided to freeze protect the coach to be on the safe side.
We made a two day trip back to Texas to get into warm weather.

[JimF]

Originally Posted by CaptainJustice

Fan starts in response to thermostat setting, never gets any heat, then fan shuts down within about 15 seconds. Can turn off, wait, and replicate.



Rear furnace working just fine so it's not a general propane delivery problem. I'm on the road and it's cold! Anyone with ideas?

Had the same last winter, 175.00 service call and a new circuit board it works fine. Had the same exact symptoms as you. Can't understand however why it's cold in the living area of your 378, which is what we have. We use the fireplace and a small portable heater up front, the front furnace never comes on even when the temps are down in the single digits.



JimF

[tilap]

I had the same problem a few weeks ago. Took it to a RV repair shop. The first question fm the tech after he noticed my dogs "how clean is the unit?" I don't have a clue my answer was. Took the front cover off cleaned up all the dust and the dog hair from the little vent on the side and the top. Turned the heat on and work since then. So long story to say $127.00 to have a tech cleaning dogs hair.

[The Otters]

I hope you already figured this out...

I'm not familiar with this furnace but what you described is flaming out. There will be a sensor in front of the chamber that the flame rises into. It will look like a thin 3/16 -1/8 in diameter metal probe maybe a couple inches long. Remove it, take your wifes nail file or very fine sandpaper, like plumbing cloth and polish the carbon off of it. That little bit of carbon is enough to not allow the probe to register. It doesn't take much to create this problem...looks like a very fine film, that's all
this might resolve your issue...

[The Otters]

This is all I have..
the metal probe is on the other side ...

[CaptainJustice]

Originally Posted by CaptainJustice

Fan starts in response to thermostat setting, never gets any heat, then fan shuts down within about 15 seconds. Can turn off, wait, and replicate.

Rear furnace working just fine so it's not a general propane delivery problem.

Pulled the front off of the furnace. Found the probe several of you discussed. All I had to do was wiggle one of the spade connectors to the probe. This is a new unit, but a 2016 model so I'm guessing just enough corrosion built up to create too much resistance. Worked all day today.

Thanks for all the feedback!

[JBP]

Good easy fix. Still very frustratingly. Safe travels.

[CaptainJustice]

Originally Posted by CaptainJustice

Pulled the front off of the furnace. Found the probe several of you discussed. All I had to do was wiggle one of the spade connectors to the probe. This is a new unit, but a 2016 model so I'm guessing just enough corrosion built up to create too much resistance. Worked all day today.

Thanks for all the feedback!

Until it didn't. The "probe" turns out to be the high limit switch and the "fix" no longer works. So I still don't know what is causing it not to start. I'm in Greensboro, NC now and a LOT warmer so not much of an issue now.

[5picker]

Originally Posted by CaptainJustice

Until it didn't. The "probe" turns out to be the high limit switch and the "fix" no longer works. So I still don't know what is causing it not to start. I'm in Greensboro, NC now and a LOT warmer so not much of an issue now.

Captain, the 'probe' you referenced (the high limit switch) and the 'probe' Otter referenced, (flame sensor) are two different components. You might want to take another look and see if what Otter pointed out could be the culprit.

[SimoRandy]

Just for clarification on my 369...

I only have one furnace (2 ac units and thermstats) and it seems to be controlled by the front thermostat. The rear thermostat doesn't seem to have an effect on the furnace. It does however work independently on the ac and heat strips. Am I missing something here? Does your model have two independent furnaces?


Randy & the Dogs
RV'rs as of 2015
2016 G-town XL 369 w/ wrangler hanging on the back!

[JBP]

That's correct the front thermostat works the furnace the rear thermostat in the front thermostat both work air conditioners independently.