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| Suburban Furnace troubles [message #145491] |
Tue, 04 October 2011 16:11  |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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Hey Guys...and a few gals...
Got problems with my Suburban furnace. Set the thermostat to 70* (or any setting for that matter) and no start...no nothing. I know, (or at least I think I know) that there is a Suburban furnace manual somewhere in the GMC archives, but am unable to find it. Does anyone know where I can find it or have any hint on what might be wrong with the furnace...where to start? Yes....it has gas...tank is full and valve at the furnace is on.
Thanks all...
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: Suburban Furnace troubles [message #145495 is a reply to message #145491] |
Tue, 04 October 2011 16:49  |
winter
Messages: 247
Registered: September 2007
Location: MPLS MN
Karma: 0
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is the fan blowing but no flame or is it not doing anything?
I had a bad house battery that was low on voltage that would make the furnace purge fan spin but it wouldn't hold a flame. changing the inverter and the battery brought the furnace back to life.
Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota
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| Re: Suburban Furnace troubles [message #145508 is a reply to message #145491] |
Tue, 04 October 2011 17:49 |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
Karma: 0
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| Larry wrote on Tue, 04 October 2011 16:11 |
Hey Guys...and a few gals...
Got problems with my Suburban furnace. Set the thermostat to 70* (or any setting for that matter) and no start...no nothing. I know, (or at least I think I know) that there is a Suburban furnace manual somewhere in the GMC archives, but am unable to find it. Does anyone know where I can find it or have any hint on what might be wrong with the furnace...where to start? Yes....it has gas...tank is full and valve at the furnace is on.
Thanks all...
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http://bdub.net/manuals/index.html
scroll down to find the manual; there are several to choose from.
as to it not running check the plug on the right side of unit to see if you have 12 volts there. if you have 12V but still no action check the thermostat to see if you are getting 12V out of it. if not so then you will have to pull the furnace and start checking.
to pull it remove the front panel and there should be 2 screws going down into the floor; disconnect wiring and propane line and duct hoses. the duct terminate in metal ends that slide into the casing. outside the coach there is a screw in the center of the exhaust vent to remove. then the unit should slide out of the housing.
Fred V
'77 Royale RB 455
P'cola, Fl
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| Re: Suburban Furnace troubles [message #145685 is a reply to message #145539] |
Thu, 06 October 2011 07:34 |
Erv Troyer
Messages: 125
Registered: February 2004
Location: Lagrange, IN
Karma: 0
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[quote title=Larry wrote on Tue, 04 October 2011 20:20
Nope...no fan, no flame, nothing happends. I have 12v to the thermostat. Need to check at the furnace.
Any other ideas?
[/quote]
Larry, if you have 12v at the thermostat then you have 12v at the furnace. (I assume you are using a volt meter and NOT a test light.) Check the thermostat circuit at the furnace by shorting across the two wires that go to the thermostat (this eliminates t-stat and wires to t-stat). The blower relay should close in about 15 seconds, then ignition should occur 7-8 seconds after that. If nothing happens then you have a dead blower relay, dead blower motor, or a loose wire.
Quick review of normal operating sequence:
1 Thermostat closes, energizes blower relay
2 in about 15 seconds blower relay closes, blower starts
3 air prover switch on blower closes, power goes to control board
4 after 7 second purge cycle the control board sends 12v to gas valve and high voltage to Ignitor electrode
5 burner lights, sensor electrode sends OK signal to control board, and flame continues to burn.
NOTE: some earlier models did not have the delay on the blower relay, and some control boards did not have the 7 second purge cycle.
Hope that helps.
Erv Troyer Lagrange, IN
74 Sequoia
reo43@aol.com
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| Re: Suburban Furnace troubles [message #145694 is a reply to message #145685] |
Thu, 06 October 2011 08:52 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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[quote title=Erv Troyer wrote on Thu, 06 October 2011 07:34
Larry, if you have 12v at the thermostat then you have 12v at the furnace. (I assume you are using a volt meter and NOT a test light.) Check the thermostat circuit at the furnace by shorting across the two wires that go to the thermostat (this eliminates t-stat and wires to t-stat). The blower relay should close in about 15 seconds, then ignition should occur 7-8 seconds after that. If nothing happens then you have a dead blower relay, dead blower motor, or a loose wire.
Quick review of normal operating sequence:
1 Thermostat closes, energizes blower relay
2 in about 15 seconds blower relay closes, blower starts
3 air prover switch on blower closes, power goes to control board
4 after 7 second purge cycle the control board sends 12v to gas valve and high voltage to Ignitor electrode
5 burner lights, sensor electrode sends OK signal to control board, and flame continues to burn.
NOTE: some earlier models did not have the delay on the blower relay, and some control boards did not have the 7 second purge cycle.
Hope that helps.[/quote]
Ed,
Thanks for the note. I found 12v at the thermostat, but not at the furnace. So Iooked closer at the thermostat. It is an after-market thermostat from Fleet Farm Supply. It has a shut off function on it so that when exposed to temps below 50* it can't come on. The notch that it slips into for full shut off, lifts a contact strip to break contact with the blower, so that no matter the temp, the furnace cannot come on. This contact strip is pivoted in the middle of the strip. Somehow, the strip pivoted at the center of the strip and therefore failed to make contact when the temp was turned up. I pivoted the strip back where it belongs and VOILA!!....it fired. Finally!!!....a simple fix on my GMC!!
Larry
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: [GMCnet] Suburban Furnace troubles [message #146056 is a reply to message #145491] |
Mon, 10 October 2011 09:56 |
George DV
Messages: 132
Registered: August 2004
Karma: 0
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Senior Member |
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Larry
I might be late to the party, having been gone on trip to Hershey recently
since Goshen, but I lived with an annoying intermittent furnace power-on for
a year or more and never found the culprit.......... til recently.
I bought a NOS modern blade fuse block [12 pos.] from Bontrager in Indiana
rally time [White Pidgeon] for $8 and installed it after Goshen.
When I switched over the leads from the OEM fuse panel, I discovered that
the power out lead to the furnace was brittle and fell off in pieces.
It seems the conductor wire under the insulation right at the output from
the old fuse panel had disintegrated and only the insulation held it
together. Occasionally.
Hence the wire conducted only when the moon was right, or the Karma was
good..
I spliced a new short lead into the new fuse block and it is fixed!.
How would I ever find that on purpose.
Had a wonderful trip to Hershey.
Got a lot of interest in the GMC and gave out all the club pamphlets I had
which was 9.
Need more.
I think we have some new converts coming and found at least 3 new TZE's.
Also coming.
One fellow {Carl?} from Syossset, LI, NY has a coach and the VIN Plate is
missing but he promised to send me the TZE when he gets home.
Another long time coach owner who was not aware of our group is going to
join by mail.
And yet another, a wannabee, is going to keep in touch with me in emails in
his persuit of a coach.
And lastly, one spectator there approached me and gave me a Hot Wheels GMC
he bought on site; said he knew who really needed it.
What a guy ! [I usually reserve that comment for Obami].
George DV
_____________
/ ][ ] [ ] [ ] \
o O-----------O-----O-o
1976 GLENBROOK
TZE 166V 100976
455 HEI 3.70
225 Uniroyals/Alcoas
Beautiful Upstate NY
----- Original Message -----
From: "Larry" <weidnerl@wwt.net>
To: <gmclist@temp.gmcnet.org>
Sent: Tuesday, October 04, 2011 5:11 PM
Subject: [GMCnet] Suburban Furnace troubles
>
>
> Hey Guys...and a few gals...
>
> Got problems with my Suburban furnace. Set the thermostat to 70* (or any
> setting for that matter) and no start...no nothing. I know, (or at least I
> think I know) that there is a Suburban furnace manual somewhere in the GMC
> archives, but am unable to find it.
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| Re: [GMCnet] Suburban Furnace troubles [message #146065 is a reply to message #146058] |
Mon, 10 October 2011 10:46 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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The Suburban Furnaces all have a common trait. I would not say that is a
fault exactly, but they require full battery voltage to work properly. When
the thermostat demands heat, the fan blower comes on. In the fan plenum,
there is a micro switch that is activated by the air output from the blower.
If there is not enough air pressure, (low fan speed), the switch will not
close, and the burner will not light. The fan will continue to run and
freeze your patooties off. I fought a cranky one for months before admitting
defeat and replacing the thing. I gave it to Bill Guise for parts. Furnaces
are something that used properly are a great device. They require seasonal
maintence, and DO NOT like mud dauber nests in the heat exchanger. If you
see them flying in and out of your external intake & exhaust vents, take
your shop vac and dispense with them before they decide to build a permanent
home there. It seem that they are attracted to the odorant that we find
repulsive in Propane.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Mon, Oct 10, 2011 at 8:08 AM, Jim Kanomata <jimkanomata@gmail.com> wrote:
> You'll find that the Furnace requires 13 volts or mere , if not it
> does not want to ignite.
> The blower will run but no heat.
>
>
> --
> Jim Kanomata
> Applied/GMC, Fremont,CA
> jimk@appliedairfilters.com
> http://www.appliedgmc.com
> 1-800-752-7502
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