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[GMCnet] Furnace problems [message #40676] Fri, 17 April 2009 12:56 Go to next message
kenneth hugelier is currently offline  kenneth hugelier   United States
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This problem is starting to get on my nerves. I'm hoping for a little help here. My 30K btu Suburban furnace which, according to the records I got from the PO, was replaced in the mid-nineties, does not work according to "hoil". When I set the thermostat and turn the switch on,  the furnace fires up after the correct wait time and the fan starts and it produces heat for about 3 to 4 minutes. The flame then goes out and (with a new "Dinasaur" ignition board) tries to start three times then shuts off. I replaced the ignition board (see above). I called Dinasaur and was talked through some simple checks using a VOM. The high tension ignition wire is good the coil on the new board is good, the jumper is removed. Dinasaur sent me a new board (second one) and I got the same results. I checked the gas pressure with a water column and it is set at 10 inches. I jumped out the thermostat to no avail. The only thing left is the gas valve, but before I spend
more money, I thought I would try to get some help here. Help anyone?


ken hugelier
77 PB
Det. Mich.
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Re: [GMCnet] Furnace problems [message #40677 is a reply to message #40676] Fri, 17 April 2009 13:15 Go to previous messageGo to next message
GMCWiperMan is currently offline  GMCWiperMan   United States
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Ken,

I know little about those furnaces, but it sounds me like you need to put an
ammeter in series with the gas valve. Sounds to me like its coil is opening
when it warms up; if you don't get current flow during the restart attempts,
you'll have that answer.

Ken Henderson
Americus, GA
GMCWipersEtc.com
’76 X-Birchaven

-----Original Message-----
...  the furnace fires up after the correct wait time and the fan starts and
it produces heat for about 3 to 4 minutes. The flame then goes out and (with
a new "Dinasaur" ignition board) tries to start three times then shuts
off... The only thing left is the gas valve...
ken hugelier

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Re: [GMCnet] Furnace problems [message #40679 is a reply to message #40676] Fri, 17 April 2009 13:23 Go to previous messageGo to next message
storm'n is currently offline  storm'n   United States
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Sounds like the hi-temp safety switch is kicking it out. Put a jumper across & see if it still kicks out. Don't leave it unattended this way. Have you got good hot air circulation?

--- On Fri, 4/17/09, ken hugelier <kahugelier@sbcglobal.net> wrote:


From: ken hugelier <kahugelier@sbcglobal.net>
Subject: [GMCnet] Furnace problems
To: gmclist@temp.gmcnet.org
Received: Friday, April 17, 2009, 1:56 PM


This problem is starting to get on my nerves. I'm hoping for a little help here. My 30K btu Suburban furnace which, according to the records I got from the PO, was replaced in the mid-nineties, does not work according to "hoil". When I set the thermostat and turn the switch on,  the furnace fires up after the correct wait time and the fan starts and it produces heat for about 3 to 4 minutes. The flame then goes out and (with a new "Dinasaur" ignition board) tries to start three times then shuts off. I replaced the ignition board (see above). I called Dinasaur and was talked through some simple checks using a VOM. The high tension ignition wire is good the coil on the new board is good, the jumper is removed. Dinasaur sent me a new board (second one) and I got the same results. I checked the gas pressure with a water column and it is set at 10 inches. I jumped out the thermostat to no avail. The only thing left is the gas valve, but before I spend
more money, I thought I would try to get some help here. Help anyone?


ken hugelier
77 PB
Det. Mich.
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Re: [GMCnet] Furnace problems [message #40683 is a reply to message #40679] Fri, 17 April 2009 13:44 Go to previous messageGo to next message
idrob is currently offline  idrob   United States
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storm'n wrote on Fri, 17 April 2009 11:23

Sounds like the hi-temp safety switch is kicking it out. Put a jumper across & see if it still kicks out. Don't leave it unattended this way. Have you got good hot air circulation?

--- On Fri, 4/17/09, ken hugelier <kahugelier@sbcglobal.net> wrote:


From: ken hugelier <kahugelier@sbcglobal.net>
Subject: [GMCnet] Furnace problems
To: gmclist@temp.gmcnet.org
Received: Friday, April 17, 2009, 1:56 PM


This problem is starting to get on my nerves. I'm hoping for a little help here. My 30K btu Suburban furnace which, according to the records I got from the PO, was replaced in the mid-nineties, does not work according to "hoil". When I set the thermostat and turn the switch on,  the furnace fires up after the correct wait time and the fan starts and it produces heat for about 3 to 4 minutes.
(snip)
The only thing left is the gas valve, but before I spend
more money, I thought I would try to get some help here. Help anyone?


ken hugelier
77 PB
Det. Mich.




The high temp switch is very suspect, as was mentioned above. Bridge it and try another attempt to see if it stays on. They are a normally closed bi metalic snap switch, and when they get tired, they conduct when they want and then with heat the spring pressure is not enough to keep the contacts closed. The other thing is the fan sail switch, which may be dropping out if the fan slows down after running a little. That can happen due to either low voltage, or just a tired fan. More common for them to start slow and speed up, but I have seen it happen that they slow down with time too. I also had a sail switch that was just bent enough so it was erratic in operation. I bent it back to original, and it was then fine.

I'll bet on the high temp switch though.




Rob Allen
former owner of '76 x-PB
Re: [GMCnet] Furnace Problems [message #40706 is a reply to message #40676] Fri, 17 April 2009 18:07 Go to previous messageGo to next message
kenneth hugelier is currently offline  kenneth hugelier   United States
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OK, now that's what I'm talkin' about. Good suggestions. Norm and Rob; the temp. limit is a good one and I like it because it is the cheapest! I just have to locate it. The coil on the gas valve crossed my mind, but I was hoping it wasn't because I'm not sure if it is replaceable separately and if not, would mean replacing the whole valve $$$. I will get at it tomorrow and let you all know what I find. Thanks.


ken hugelier
77 PB
Det. Mich.
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Re: [GMCnet] Furnace Problems [message #40715 is a reply to message #40706] Fri, 17 April 2009 19:50 Go to previous messageGo to next message
roy1 is currently offline  roy1   United States
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Ken

Did you put a voltmeter across the coil of the gas valve when it is trying to start( the spark will be clicking at this time).
If there is power to the valve at this time and you can see the spark is good the flapper in the valve is possibly stuck closed. Another possibility is the burner rack may need to be cleaned.



Roy


Roy Keen Minden,NV 76 X Glenbrook
Re: [GMCnet] Furnace problems [message #40733 is a reply to message #40676] Fri, 17 April 2009 23:02 Go to previous messageGo to next message
kenneth hugelier is currently offline  kenneth hugelier   United States
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I just ran across  my post thanking people for giving me suggestions and I note that I forgot to thank Mr. Henderson for the gas valve suggestion. I also see further down that Roy has talked about the gas valve as well. Thanks again guys, It has to be one of those things.


ken hugelier
77 PB
Det. Mich.
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Re: [GMCnet] Furnace problems [message #40734 is a reply to message #40676] Fri, 17 April 2009 23:11 Go to previous messageGo to next message
whmckinley is currently offline  whmckinley   United States
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Have you checked the fly switch (I think that was what it was called) , Mine had a switch that would be closed when the fan was up to speed. If it didn't blow enough air, IE: inlet blocked, dirty squirrel cage, flakey blower motor, the air paddle inside the outlet chamber wouldn't move enough to close the switch. It would shut down after 3 minutes. Mine was caused by a flakey blower motor, pulled it apart, cleaned and oiled it. Didn't have the problem afterward. That was on my previous SOB. Putting a new furnace in my GMC during the rebuild.

Bill 1973 Glacier 26ft bowling alley with wheels
Re: [GMCnet] Furnace problems [message #40786 is a reply to message #40734] Sat, 18 April 2009 13:12 Go to previous messageGo to next message
emerystora is currently offline  emerystora   United States
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On Apr 17, 2009, at 10:11 PM, william mckinley wrote:

>
>
> Have you checked the fly switch (I think that was what it was
> called) , Mine had a switch that would be closed when the fan was up
> to speed. If it didn't blow enough air, IE: inlet blocked, dirty
> squirrel cage, flakey blower motor, the air paddle inside the outlet
> chamber wouldn't move enough to close the switch. It would shut down
> after 3 minutes. Mine was caused by a flakey blower motor, pulled it
> apart, cleaned and oiled it. Didn't have the problem afterward. That
> was on my previous SOB. Putting a new furnace in my GMC during the
> rebuild.
> --
> Bill
> 1973 Glacier
> 26ft bowling alley with wheels
>
That is called a "sail" switch. I was just going to suggest that when
I read your message.


Emery Stora
77 Kingsley
Santa Fe, NM


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Re: [GMCnet] Furnace Problems [message #41000 is a reply to message #40676] Mon, 20 April 2009 22:00 Go to previous messageGo to next message
kenneth hugelier is currently offline  kenneth hugelier   United States
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Do we have a good place for Suburban furnace parts other than directly from the Manufacturer? I'm still workin' on that little sucker and I feel the need for a couple parts.


ken hugelier
77 PB
Det. Mich.
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Re: [GMCnet] Furnace Problems [message #41014 is a reply to message #41000] Tue, 21 April 2009 07:52 Go to previous messageGo to next message
Tom Lins is currently offline  Tom Lins   United States
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kenneth hugelier wrote on Mon, 20 April 2009 23:00

Do we have a good place for Suburban furnace parts other than directly from the Manufacturer? I'm still workin' on that little sucker and I feel the need for a couple parts.


ken hugelier
77 PB
Det. Mich.
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Ken
Which model suburban do you have?


Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, Aluminum Radiator Quad-Bag Suspension Solar Panel
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Re: [GMCnet] Furnace problems [message #41026 is a reply to message #40676] Tue, 21 April 2009 08:24 Go to previous messageGo to next message
kenneth hugelier is currently offline  kenneth hugelier   United States
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I have an NT 30. The parts list shows a limit switch and a paddle switch and a relay. I'm leaning toward the limit switch as being the source of my problem. Thanks.


ken hugelier
77 PB
Det. Mich.
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Re: [GMCnet] Furnace problems [message #41027 is a reply to message #41026] Tue, 21 April 2009 08:34 Go to previous messageGo to next message
C Boyd is currently offline  C Boyd   United States
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kenneth hugelier wrote on Tue, 21 April 2009 09:24

I have an NT 30. The parts list shows a limit switch and a paddle switch and a relay. I'm leaning toward the limit switch as being the source of my problem. Thanks.


ken hugelier
77 PB
Det. Mich.
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Sir: This may not be your issue, bit I had a house unit that would fire up, run a little and shut down. Turned out the burner box had a hole in it and was allowing fire and too much heat to the vents. High limit was kicking for a reason..


C. Boyd
76 Crestmont
East Tennessee
Re: [GMCnet] Furnace problems [message #41047 is a reply to message #40676] Tue, 21 April 2009 10:59 Go to previous messageGo to next message
kenneth hugelier is currently offline  kenneth hugelier   United States
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Thanks for the reply. I have a plug-in CO detector in the house. I can plug it in to the coach while it's in the drive on shore power and fire up the furnace and maybe see if I have a combustion chamber leak. Hope not, because that means new furnace time.


ken hugelier
77 PB
Det. Mich.
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Re: [GMCnet] Furnace problems [message #41048 is a reply to message #41047] Tue, 21 April 2009 11:22 Go to previous messageGo to next message
C Boyd is currently offline  C Boyd   United States
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kenneth hugelier wrote on Tue, 21 April 2009 11:59

Thanks for the reply. I have a plug-in CO detector in the house. I can plug it in to the coach while it's in the drive on shore power and fire up the furnace and maybe see if I have a combustion chamber leak. Hope not, because that means new furnace time.


ken hugelier
77 PB
Det. Mich.
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Ken: In my case I also have a pulg in detector but being the idiot I am, I had it plugged in close to the return air filter instead of closest to the burner in the bedroom. So the detector did not work in my case.. I was fortunate the high limit did its job..


C. Boyd
76 Crestmont
East Tennessee
Re: [GMCnet] Furnace problems [message #41106 is a reply to message #41026] Tue, 21 April 2009 18:35 Go to previous messageGo to next message
fred v is currently offline  fred v   United States
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kenneth hugelier wrote on Tue, 21 April 2009 08:24

I have an NT 30. The parts list shows a limit switch and a paddle switch and a relay. I'm leaning toward the limit switch as being the source of my problem. Thanks.


ken hugelier
77 PB
Det. Mich.
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don't just throw money at a problem. find the problem. did you download the manual? it has a great diagnostic section.


Fred V
'77 Royale RB 455
P'cola, Fl
Re: [GMCnet] Furnace Problems [message #41127 is a reply to message #40676] Tue, 21 April 2009 21:37 Go to previous messageGo to next message
kenneth hugelier is currently offline  kenneth hugelier   United States
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Fred,
     If you mention the site where I can download and print the diagnostic part of the manual, it would save me a lot of time. Thanks.


ken hugelier
77 PB
Det. Mich.
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Re: [GMCnet] Furnace Problems [message #41129 is a reply to message #41127] Tue, 21 April 2009 21:48 Go to previous messageGo to next message
emerystora is currently offline  emerystora   United States
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On Apr 21, 2009, at 8:37 PM, ken hugelier wrote:

> Fred,
> If you mention the site where I can download and print the
> diagnostic part of the manual, it would save me a lot of time. Thanks.
>
>
> ken hugelier
> 77 PB
> Det. Mich.
>
Ken
If you can tell me what model you have I probably have a pdf file that
I can email to you.

Emery Stora
77 Kingsley
Santa Fe, NM


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Re: [GMCnet] Furnace Problems [message #41139 is a reply to message #40676] Tue, 21 April 2009 22:54 Go to previous messageGo to next message
kenneth hugelier is currently offline  kenneth hugelier   United States
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Emory,
        My furnace is an NT 30SP. C. Boyd sent me a pdf for an NT30M & MD. I don't know what the difference is but the diagnostic portion looks helpful. If there is a difference of any consequence, it would be helpful to know what it is. Thanks. 


ken hugelier
77 PB
Det. Mich.
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Re: [GMCnet] Furnace Problems [message #41147 is a reply to message #41127] Wed, 22 April 2009 07:20 Go to previous messageGo to previous message
fred v is currently offline  fred v   United States
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kenneth hugelier wrote on Tue, 21 April 2009 21:37

Fred,
     If you mention the site where I can download and print the diagnostic part of the manual, it would save me a lot of time. Thanks.


ken hugelier
77 PB
Det. Mich.



http://bdub.net/manuals/index.html
lots of good stuff here.


Fred V
'77 Royale RB 455
P'cola, Fl
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