DuoTherm furnace 90130.002 won't fire

G

gmcnet1

Member
Apr 23, 2019
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Looking for some troubleshooting help on my furnace. I got the coach 1.5 years ago and successfully used the furnace once. Now when I try to light it,
no luck. The fan runs and I hear the igniter attempting to light a couple of times (I can see a glow in the viewport). I have cycled it several times.
The furnace gas valve is open (handle inline with the valve). I have lit all burners on the stove. There are no obstructions visible in the exterior
intake/exhaust ports. I removed the furnace front panel and nothing looks weird. If I operate the sail switch I can hear it clicking.

It almost seems like gas isn't flowing but I'm not sure how to test.
--
Christo Darsch
GMC Nor'easters
1977 Eleganza II - "The Komet"
3.50 Power Drive, Disc Brakes, Alcoas
Weymouth, MA
 
Have you lit the pilot light

On Sat, Sep 5, 2020, 17:35 Christo Darsch via Gmclist <

> Looking for some troubleshooting help on my furnace. I got the coach 1.5
> years ago and successfully used the furnace once. Now when I try to light
> it,
> no luck. The fan runs and I hear the igniter attempting to light a couple
> of times (I can see a glow in the viewport). I have cycled it several times.
> The furnace gas valve is open (handle inline with the valve). I have lit
> all burners on the stove. There are no obstructions visible in the exterior
> intake/exhaust ports. I removed the furnace front panel and nothing looks
> weird. If I operate the sail switch I can hear it clicking.
>
> It almost seems like gas isn't flowing but I'm not sure how to test.
> --
> Christo Darsch
> GMC Nor'easters
> 1977 Eleganza II - "The Komet"
> 3.50 Power Drive, Disc Brakes, Alcoas
> Weymouth, MA
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Make sure the batter is at 14.5 volt or mre as the unit likes to fire up
only when voltage is high.
Also turn burners on the stove to help purge the LPG closer to the furnace;

On Sat, Sep 5, 2020 at 3:45 PM Sammy Williams via Gmclist <

> Have you lit the pilot light
>
>
> On Sat, Sep 5, 2020, 17:35 Christo Darsch via Gmclist <

>
> > Looking for some troubleshooting help on my furnace. I got the coach 1.5
> > years ago and successfully used the furnace once. Now when I try to light
> > it,
> > no luck. The fan runs and I hear the igniter attempting to light a couple
> > of times (I can see a glow in the viewport). I have cycled it several
> times.
> > The furnace gas valve is open (handle inline with the valve). I have lit
> > all burners on the stove. There are no obstructions visible in the
> exterior
> > intake/exhaust ports. I removed the furnace front panel and nothing looks
> > weird. If I operate the sail switch I can hear it clicking.
> >
> > It almost seems like gas isn't flowing but I'm not sure how to test.
> > --
> > Christo Darsch
> > GMC Nor'easters
> > 1977 Eleganza II - "The Komet"
> > 3.50 Power Drive, Disc Brakes, Alcoas
> > Weymouth, MA
> >
> > _______________________________________________
> > 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, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502
 
There is no pilot light.
--
Christo Darsch
GMC Nor'easters
1977 Eleganza II - "The Komet"
3.50 Power Drive, Disc Brakes, Alcoas
Weymouth, MA
 
I am connected to shore power, batteries are fully charged. As I said in my initial post I have lit all burners on the stove.
--
Christo Darsch
GMC Nor'easters
1977 Eleganza II - "The Komet"
3.50 Power Drive, Disc Brakes, Alcoas
Weymouth, MA
 
Still check the voltage at the furnace.

JR Wright
Michigan

>
> I am connected to shore power, batteries are fully charged. As I said in my initial post I have lit all burners on the stove.
> --
> Christo Darsch
> GMC Nor'easters
> 1977 Eleganza II - "The Komet"
> 3.50 Power Drive, Disc Brakes, Alcoas
> Weymouth, MA
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Did you check to see if there is 12.7 or so dc volts on the gas valve when the igniter was clicking? If so it should have fired if there is power
and it didn’t you probably have a bad gas valve ( stuck closed or bad coil or there could be no gas to the valve due to a valve turned off)
--
Roy Keen
Minden,NV
76 X Glenbrook
 
I have 13.8V to the furnace and when I hear it click to try to light I get voltage at the gas solenoid. Should I be able to smell gas outside at the
furnace exhaust when this happens and it doesn’t light?

Here’s a video of the startup sequence. The igniter glows intermittently rather than steadily. Is this normal?

https://www.gmcmhforum.com/threads/duotherm-furnace-not-lighting.875/
--
Christo Darsch
GMC Nor'easters
1977 Eleganza II - "The Komet"
3.50 Power Drive, Disc Brakes, Alcoas
Weymouth, MA
 
Shouldn’t smell gas . If you have 13.8 volts at the gas valve with the igniter sparking the gas valve is most likely stuck closed. This happened to
me I took the valve apart and cleaned the seat with alcohol that fixed it. Most folks replace the valve with a new one they don’t cost much. The
spark gap could be wrong but most likely not.
--
Roy Keen
Minden,NV
76 X Glenbrook
 
I don't smell gas inside, only outside from the furnace exhaust when it's trying (and failing) to light. The gas has to go somewhere! I think the gas
valve is working okay.

Does anyone know if this furnace is supposed to go tic-tic-tic like a domestic stove when it's trying to light? It's not doing that.
--
Christo Darsch
GMC Nor'easters
1977 Eleganza II - "The Komet"
3.50 Power Drive, Disc Brakes, Alcoas
Weymouth, MA
 
If you detected a whiff of gas at the exhaust and it isn’t going tic tic tic you found the problem the spark ignition isn’t working now you need
to figure out why?
--
Roy Keen
Minden,NV
76 X Glenbrook
 
Yep, I'll probably tackle this after my upcoming camping weekend in mid-September. Thanks all!
--
Christo Darsch
GMC Nor'easters
1977 Eleganza II - "The Komet"
3.50 Power Drive, Disc Brakes, Alcoas
Weymouth, MA
 
I have personally never used the RV stock propane heater. I simply take an
electric room heater and plug it in. Keeps the entire RV room nice and warm
without all the headaches of propane. Stoves: use the portable Coleman
stove or the microwave the RV has.
Sammy Williams

SOB owner :) (1999 American Eagle)

On Mon, Sep 7, 2020 at 11:17 AM Christo Darsch via Gmclist <

> Yep, I'll probably tackle this after my upcoming camping weekend in
> mid-September. Thanks all!
> --
> Christo Darsch
> GMC Nor'easters
> 1977 Eleganza II - "The Komet"
> 3.50 Power Drive, Disc Brakes, Alcoas
> Weymouth, MA
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
You get where it's cold enough, you will hug your furnace. Electric heaters
take the chill off fairly well, but are no match for a 30,000 btu furnace
with forced air. We winter camp, and use ours often. Neglect it for a long
stretch, and you are seeing the results. If you have the original furnace
that came in 1973, pull it out and smash it to bits. I replaced my oem
furnace with a suburban. It still works great. But, do not neglect your
visual inspection of the heat exchanger. If it is cracked, replace it, or
the entire furnace. Carbon monoxide detectors in the coach are essential,
and test them often, too.
Jim Hupy
Salem, Oregon

On Mon, Sep 7, 2020, 11:09 AM Sammy Williams via Gmclist <

> I have personally never used the RV stock propane heater. I simply take an
> electric room heater and plug it in. Keeps the entire RV room nice and warm
> without all the headaches of propane. Stoves: use the portable Coleman
> stove or the microwave the RV has.
> Sammy Williams
>
> SOB owner :) (1999 American Eagle)
>
> On Mon, Sep 7, 2020 at 11:17 AM Christo Darsch via Gmclist <

>
> > Yep, I'll probably tackle this after my upcoming camping weekend in
> > mid-September. Thanks all!
> > --
> > Christo Darsch
> > GMC Nor'easters
> > 1977 Eleganza II - "The Komet"
> > 3.50 Power Drive, Disc Brakes, Alcoas
> > Weymouth, MA
> >
> > _______________________________________________
> > 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
>
 
It may have to do with location, too. In SC, it never gets really cold
enough for a furnace. :)

On Mon, Sep 7, 2020 at 1:40 PM James Hupy via Gmclist <

> You get where it's cold enough, you will hug your furnace. Electric heaters
> take the chill off fairly well, but are no match for a 30,000 btu furnace
> with forced air. We winter camp, and use ours often. Neglect it for a long
> stretch, and you are seeing the results. If you have the original furnace
> that came in 1973, pull it out and smash it to bits. I replaced my oem
> furnace with a suburban. It still works great. But, do not neglect your
> visual inspection of the heat exchanger. If it is cracked, replace it, or
> the entire furnace. Carbon monoxide detectors in the coach are essential,
> and test them often, too.
> Jim Hupy
> Salem, Oregon
>
> On Mon, Sep 7, 2020, 11:09 AM Sammy Williams via Gmclist <

>
> > I have personally never used the RV stock propane heater. I simply take
> an
> > electric room heater and plug it in. Keeps the entire RV room nice and
> warm
> > without all the headaches of propane. Stoves: use the portable Coleman
> > stove or the microwave the RV has.
> > Sammy Williams
> >
> > SOB owner :) (1999 American Eagle)
> >
> > On Mon, Sep 7, 2020 at 11:17 AM Christo Darsch via Gmclist <

> >
> > > Yep, I'll probably tackle this after my upcoming camping weekend in
> > > mid-September. Thanks all!
> > > --
> > > Christo Darsch
> > > GMC Nor'easters
> > > 1977 Eleganza II - "The Komet"
> > > 3.50 Power Drive, Disc Brakes, Alcoas
> > > Weymouth, MA
> > >
> > > _______________________________________________
> > > 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
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
The furnace is not the original Sol-Aire; it's an older replacement but it looks to be in good shape. I have a combo CO/propane detector mounted low
in the coach. Thanks for the tips! I expect to use the furnace regularly once I get it going. I've only had the coach for about a year and a half.
--
Christo Darsch
GMC Nor'easters
1977 Eleganza II - "The Komet"
3.50 Power Drive, Disc Brakes, Alcoas
Weymouth, MA
 
It really sounds ignition related. There is a pair of electrodes that sit
in front of the burner tip. If they are not close enough together, the
ignition spark will find another way to ground, and no spark, no igniting
the incoming propane. They can be easily bent closer together. Sometimes a
quick and easy fix.
Jim Hupy
Salem, Oregon

On Mon, Sep 7, 2020, 2:44 PM Christo Darsch via Gmclist <

> The furnace is not the original Sol-Aire; it's an older replacement but it
> looks to be in good shape. I have a combo CO/propane detector mounted low
> in the coach. Thanks for the tips! I expect to use the furnace regularly
> once I get it going. I've only had the coach for about a year and a half.
> --
> Christo Darsch
> GMC Nor'easters
> 1977 Eleganza II - "The Komet"
> 3.50 Power Drive, Disc Brakes, Alcoas
> Weymouth, MA
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
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