Home » Public Forums » GMCnet » Furnace from hell returns
| Furnace from hell returns [message #294138] |
Thu, 21 January 2016 10:03  |
lance
Messages: 190
Registered: December 2004
Location: Vancouver, WA
Karma: 0
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Guys,
I haven't been on here much because everything in my coach has worked so well, thanks to all your help in the past. I hope I've repaid by helping others when I have something to contribute.
This Suburban furnace has given me troubles in the past. Turned out to be a venting issue that was easily solved and has run perfectly until . . .
Yesterday it was running when I woke up. Then it stopped, but it immediately started, then stopped, paused, did it again, then came back on, ran for five seconds and quit. I cycled the new last year, Suburban thermostat and the motor would start for one or two seconds, stop and immediately, I mean before the fan motor completely stops, it starts again for not even a second and quits.
I had to leave for work, so the warmer in my roof a/c unit did the job as I made coffee and breakfast. Only in the 40's here. Last night I turned up the thermostat and the furnace came on, got warm, and I thought, can I be that lucky? No is the answer. It did the on-off thing and died. I mean cycling the thermostat does nothing. The fuse is good. My volt meter is at the shop, so I can't test anything yet. Can't even find a paper clip to short out the two thermostat wires at the plug.
Just hoping someone has had a similar experience or advice other than buy a new furnace. Maybe a new Dno board? Anyone, Beuller?
As always, thank you.
1974 Palm Beach
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| Re: Furnace from hell returns [message #294139 is a reply to message #294138] |
Thu, 21 January 2016 10:39  |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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I'd look first at the flame sensor. In that it restarts you can consider that the stat is calling for heat. The furnace cycle starts, blower runs up and closes the safety, solenoid opens and lighter cycles. No flame sensed, it times out and shuts down. It may or may not actually light. If it doesn't, look toward the gas supply and valve, and igniter circuit. If it does light, look to the flame sensor itself. It's also possible the blower safety (called a sail) is marginal, they're famous for giving problems.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Furnace from hell returns [message #294140 is a reply to message #294138] |
Thu, 21 January 2016 11:21 |
77Royale
Messages: 461
Registered: June 2014
Location: Mid Michigan
Karma: 6
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"motor would start for one or two seconds, stop and immediately, I mean before the fan motor completely stops, it starts again for not even a second and quits."
Thats the odd part. I had issues with a dirty flame sensor which would ignite for a moment, then just cut out. That would be my suggestion to clean off the electrodes really good, But reading again your saying the blower motor shuts down. Even when mine was not lighting or staying lit, the blower motor never shut down as long as the Tstat was calling for heat.
The blower has to get going fast enough to engage the sail switch. If its as you say, the blower is shutting down thats where I would start..
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
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| Re: Furnace from hell returns [message #294150 is a reply to message #294143] |
Thu, 21 January 2016 15:59 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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Senior Member |
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Steve, Yes, you could have paid $70 for the control board and saved a little money. But, I find that sometimes it is worth it to pay someone who knows exactly what needs to be done. Back when you could repair TVs, I paid $100 for a repair, $7 worth of parts and $93 to know where they went.
I don't know what water heater you have but when I had to replace mine, I wish that I had gotten the exact same brand and model. It would have saved lots of extra work. Just something to consider.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: Furnace from hell returns [message #294165 is a reply to message #294138] |
Fri, 22 January 2016 15:52 |
lance
Messages: 190
Registered: December 2004
Location: Vancouver, WA
Karma: 0
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Senior Member |
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Thanks for the advice but the mystery remains. I pulled out the furnace and took it to the local RV repair shop. They checked the board and it was good, so they put some propane and 12 volts to it and it ran perfectly. They are experienced guys and they couldn't find anything wrong.
The shop owner said it was most likely a voltage issue and my house batteries were probably shot. They are the correct large deep cycle batteries, 36 month that are less than two years old. all battery cables and connections are new and tight with no corrosion. My 74 has the house batteries up front and I have to remove the grill and air compressor to get them out. They seem fine. I have 13 volts at the fuse panel.
So, I brought the furnace home and put it in. It fired up and ran, but it's unusually warm here today so I can't really test it until this evening. Anyone ever hear of such voltage issues?
1974 Palm Beach
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| Re: Furnace from hell returns [message #294168 is a reply to message #294138] |
Fri, 22 January 2016 16:09 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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what you need to do to check the voltage is, hang your meter on the 12V at the furnace... on the control board input if you can, or on the leads to the blower motor. Start the furnace and note the voltage drop relative to a non-running condition. The motor draws a faily heavy current, a poor connection somewhere or a low battery might drop the voltage enough to stop the furnace from working.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
[Updated on: Fri, 22 January 2016 16:10] Report message to a moderator |
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| Re: [GMCnet] Furnace from hell returns [message #294169 is a reply to message #294165] |
Fri, 22 January 2016 16:03 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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So it looks like the furnace works on the bench so that leaves three
possibilities?
Are the air inlets and outlets clear(combustion as well as ventilation)
Is the connection at the house fuse panel good? Are you certain the feed
from the panel to the furnace is good?
Propane fuel supply ?
Sully
77 royale
Seattle
On Friday, January 22, 2016, Lance wrote:
> Thanks for the advice but the mystery remains. I pulled out the furnace
> and took it to the local RV repair shop. They checked the board and it was
> good, so they put some propane and 12 volts to it and it ran perfectly.
> They are experienced guys and they couldn't find anything wrong.
>
> The shop owner said it was most likely a voltage issue and my house
> batteries were probably shot. They are the correct large deep cycle
> batteries, 36
> month that are less than two years old. all battery cables and connections
> are new and tight with no corrosion. My 74 has the house batteries up
> front and I have to remove the grill and air compressor to get them out.
> They seem fine. I have 13 volts at the fuse panel.
>
> So, I brought the furnace home and put it in. It fired up and ran, but
> it's unusually warm here today so I can't really test it until this evening.
> Anyone ever hear of such voltage issues?
> --
> 1974 Palm Beach
>
> _______________________________________________
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: Furnace from hell returns [message #294170 is a reply to message #294165] |
Fri, 22 January 2016 16:17 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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lance wrote on Fri, 22 January 2016 14:52Thanks for the advice but the mystery remains. I pulled out the furnace and took it to the local RV repair shop. They checked the board and it was good, so they put some propane and 12 volts to it and it ran perfectly. They are experienced guys and they couldn't find anything wrong.
The shop owner said it was most likely a voltage issue and my house batteries were probably shot. They are the correct large deep cycle batteries, 36 month that are less than two years old. all battery cables and connections are new and tight with no corrosion. My 74 has the house batteries up front and I have to remove the grill and air compressor to get them out. They seem fine. I have 13 volts at the fuse panel.
So, I brought the furnace home and put it in. It fired up and ran, but it's unusually warm here today so I can't really test it until this evening. Anyone ever hear of such voltage issues?
You might have low propane pressure. It should be around 10 or 11 inches water column. You can check it yourself with a gage or a homemade water column or have it checked.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] Furnace from hell returns [message #294173 is a reply to message #294169] |
Fri, 22 January 2016 16:37 |
lance
Messages: 190
Registered: December 2004
Location: Vancouver, WA
Karma: 0
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Senior Member |
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I've done all that. Good fuse, soldered connections. Fan vent on same circuit works fine.
I just turned up the thermostat and nothing. The furnace will not start. 12 volts at the furnace, good connections. I wiggled and jiggled, but nothing. I cycled the switch on the furnace several times, nothing. I replaced the converter last year with an Intellicharge converter. No other electrical issues.
What a mystery! It ran at the RV shop. It ran for one minute after I re-installed it. Now it's a boat anchor. even shorting out the thermostat wires does nothing.
I'm baffled. Anyone?
1974 Palm Beach
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| Re: Furnace from hell returns [message #294201 is a reply to message #294138] |
Sat, 23 January 2016 10:27 |
Bill Shourt
Messages: 33
Registered: January 2005
Location: Sherman Oaks ,Ca
Karma: 0
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Member |
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I had the same problem years ago. Pulled unit four times, worked perfect on the bench. When re installed was intermittent or non start. Voltage at unit was good. Problem was that the aluminum frame where the ground lug was bolted had very slight foam overspray on it. Cleaned aluminum and lug, put anti corrosion paste on it and it has run great for the last twenty years. Good luck.
Bill and Michele Shourt
78 Kingsley, origional
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| Re: [GMCnet] Furnace from hell returns [message #294211 is a reply to message #294203] |
Sat, 23 January 2016 11:21 |
Terrance Boyd
Messages: 38
Registered: October 2008
Karma: 0
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Member |
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I have a Sunbeam NT 30. I was having a problem with it. It would start like
normal, heat to temperature, shut down. When the thermostat called for more
heat, the fan would run, but the unit would not fire up.
I went with the shotgun method. I started replacing one item at a time. The
board, over temp limit,sail switch, igniter, finally the solenoid gas
valve. The culprit was the gas valve. It is comprised of two valves in one.
It has 2 separate solenoids. Evidently when the unit was cold both valves
would operate, but when it warmed up, only one half would open, even though
I could hear the valve 'click' open. Since I replaced the valve two years
ago, it has not let me down.
Just my experience.
Terry
I think Matt and Bill have it. With that behavior you described, it sounds
like intermittent power to the fan or the main supply for the unit.
--
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: [GMCnet] Furnace from hell returns [message #294212 is a reply to message #294211] |
Sat, 23 January 2016 11:31 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Terry,
Are you saying that the "click" did not happen initially when one was not
working?
On Sat, Jan 23, 2016 at 9:21 AM, Terrance Boyd wrote:
> I have a Sunbeam NT 30. I was having a problem with it. It would start like
> normal, heat to temperature, shut down. When the thermostat called for more
> heat, the fan would run, but the unit would not fire up.
> I went with the shotgun method. I started replacing one item at a time. The
> board, over temp limit,sail switch, igniter, finally the solenoid gas
> valve. The culprit was the gas valve. It is comprised of two valves in one.
> It has 2 separate solenoids. Evidently when the unit was cold both valves
> would operate, but when it warmed up, only one half would open, even though
> I could hear the valve 'click' open. Since I replaced the valve two years
> ago, it has not let me down.
> Just my experience.
> Terry
> I think Matt and Bill have it. With that behavior you described, it sounds
> like intermittent power to the fan or the main supply for the unit.
> --
> Terry Kelpien
> ASE Master Technician
> 73 Glacier 260
> Smithfield, Va.
>
> _______________________________________________
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Furnace from hell returns [message #294214 is a reply to message #294212] |
Sat, 23 January 2016 11:53 |
Terrance Boyd
Messages: 38
Registered: October 2008
Karma: 0
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Member |
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Hi Jim.
What I am saying is I would hear the 'click' when it was working and when
it wasn't. Runs through my mind, that I would hear, 'click' 'click' when it
would fire up, but only one 'click' when it didn't. I found out that one
solenoid was bad by taking the valve out, putting 12 volts to each coil
separately.
Terry
On Jan 23, 2016 9:32 AM, "Jim Kanomata" wrote:
> Terry,
> Are you saying that the "click" did not happen initially when one was not
> working?
>
> On Sat, Jan 23, 2016 at 9:21 AM, Terrance Boyd wrote:
>
>> I have a Sunbeam NT 30. I was having a problem with it. It would start
> like
>> normal, heat to temperature, shut down. When the thermostat called for
> more
>> heat, the fan would run, but the unit would not fire up.
>> I went with the shotgun method. I started replacing one item at a time.
> The
>> board, over temp limit,sail switch, igniter, finally the solenoid gas
>> valve. The culprit was the gas valve. It is comprised of two valves in
> one.
>> It has 2 separate solenoids. Evidently when the unit was cold both valves
>> would operate, but when it warmed up, only one half would open, even
> though
>> I could hear the valve 'click' open. Since I replaced the valve two years
>> ago, it has not let me down.
>> Just my experience.
>> Terry
>> I think Matt and Bill have it. With that behavior you described, it
> sounds
>> like intermittent power to the fan or the main supply for the unit.
>> --
>> Terry Kelpien
>> ASE Master Technician
>> 73 Glacier 260
>> Smithfield, Va.
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
>
> --
> Jim Kanomata
> Applied/GMC, Fremont,CA
> jimk@appliedairfilters.com
> http://www.appliedgmc.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: [GMCnet] Furnace from hell returns [message #294215 is a reply to message #294211] |
Sat, 23 January 2016 12:06 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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"It would start like
normal, heat to temperature, shut down. When the thermostat called for more
heat, the fan would run, but the unit would not fire up."
Same thing happened to me at Bean Station. Could not get the heat, but had the fan. The fix was to shut the unit down completely for about 3 minutes and then refire it and the heat worked after that. Thought it was the sail switch at the time, so I opened the roof vents and let the furnace run continuously all night. I could still hear it cycling (turning the gas on and off), but the blower stayed on all night. It has not repeated that performance since then.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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