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Author Topic: Furnace help  (Read 523 times)

Furnace help
« on: October 24, 2017, 09:33:01 AM »
I have a question. I have a 1998 Fleetwood Bounder with a Suburban furnace SF model. I have fixed the grounding block, taped up the spark unit that's on the circuit board, and cleaned up all of the connections. The thing works great during the day, unless it's cold out, and then I have the same problem, but at night, like every other time it kicks on, it will not light and blow cold. I turn it off and back on and it lights and blows warm. I can't understand why it doesn't work and then works again 2 minutes later. Any ideas? Thanks in advance for your help.

John From Detroit

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Re: Furnace help
« Reply #1 on: October 24, 2017, 06:57:46 PM »
Too many ideas for one post but I'd start by checking the spark gap and making sure the orifice is not clogged.
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Re: Furnace help
« Reply #2 on: October 24, 2017, 07:34:05 PM »
What is your furnace model number? We need more info and the model number. Number one issue with furnaces seems to be insects getting in the combustion chamber and the sail switch sticking. When the blower starts up it pushes air through the combustion chamber and blows on what is called a sail switch. That switch tells the control card that the fan is working and air is moving through. So one basic maintenance thing is to use compressed air to blow any crud out of it.
« Last Edit: October 24, 2017, 07:37:25 PM by QZ »


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Re: Furnace help
« Reply #3 on: October 25, 2017, 08:44:56 AM »
I had a similar problem with my SF42 5 years ago.   The RV tech cleaned the unit, and replaced the thermostat t no avail.  Eventually the problem was fixed by replacing the propane regulator. What the problem was that the furnace would cycle normally several times and then sometime during the night would quit working.  I would get up, turn the furnace off and back on. I usually had to do this 3 or 4 times a night.  So I suggest that you get somebody to check  the gas pressure with a manometer.
Apex, NC
2010 Winnebago journey Express 34Y
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Re: Furnace help
« Reply #4 on: October 26, 2017, 06:55:03 PM »
Hello I have pretty much the same problem on my travel trailer.

It's fairly old (1991) and the thermostat says Suburban but I don't know what model it is, nothing shows on the heater.

In my case, the heater will work fine for the first cycle and bring the trailer to the requested temperature. It will shut the burner off and the fan will keep running for a minute or two witch is what would be expected.

The problem is that once the heater tries to start back, there will just be a loud "click" sound and the fan won't start. It will do that every 5 minutes or so and the temperature will get cooler.

I have to put the thermostat to the off position and then back to the on position and it will start back up like it's supposed for one cycle only. It's really not fun to have to get up in the middle of the night to put the thermostat off and on every time...

Any idea what it could be?

Gary RV_Wizard

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Re: Furnace help
« Reply #5 on: October 27, 2017, 09:34:59 AM »
Please identify the make & model of the furnace (not the thermostat). It's probably a Suburban furnace but there are several models with numbers like NT30 or S-11. Need to know at least whether it is a pilot light type or DSI (spark) ignition.

Your furnace seems to be in "lock out", which requires that the thermostat be turned off/on to clear. Failure of the fan to start prevents anything else from happening. There is a sensor (called the sail switch) which sits in front of the fan and measures the force of the air blowing through. Until there is a strong air flow, nothing else happens. It appears your fan start-up is failing somehow, so maybe the fan start board  or some sort of fan power source problem. Hard to say without more details on what does or doesn't happen.

Get Suburban service manuals at http://bryantrv.com/docs.html#furnace
Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL