Furnace not engaging - Page 2

Roulotte · 10-21-2023, 09:31 AM

Hi Chuck, thank you for all your input. I'm writing this on behalf of my husband: Steen. Could he possibly call you or could you call us? I'm not sure where you're located but we're in Washington State. I understand that we're not supposed to give out phone #s over the thread but it looks like I could pm you if that works. Totally understand if that doesn't work for you. Thanks again!

Roulotte · 10-21-2023, 10:56 AM

Hi,
I'm not sure where the burner assembly is, but assume it is accessed through the hatch with a small view port in it that has the gas line going into/through it. I have tried to break the connection of that line to the distribution box which I believe has the gas valve in it. That connection is so solid that I'm concerned that I'm going to break something if put more torque on the nut. With that in mind I'm about to disconnect the complete blower and squirrel cage from the burner in order to be able to get access. Is this necessary or am I going down the wrong rabbit hole? From your earlier response it sounds like it shouldn't be such an involved process to get to the igniter.
Our situation is getting a bit urgent since we pulled this Alpine 3555 up an extremely challenging road to live in while we build our home off grid, forecast is for freezing temps this next week and I'm starting to wonder if I'll be able to fix it before the weather closes in. Not possible to move the coach at this time.
Photos are of what I believe is access hatch and gas line from valve up to hatch. More photos easily provided.
Many thanks,
Steen

P.S.: I'm trying to send pictures but file was too big, will try to send separately

Roulotte · 10-21-2023, 10:58 AM

Hoping pictures can be uploaded

Roulotte · 10-21-2023, 12:12 PM

Hi,
I'm not sure where the burner assembly is, but assume it is accessed through the hatch with a small view port in it that has the gas line going into/through it. I have tried to break the connection of that line to the distribution box which I believe has the gas valve in it. That connection is so solid that I'm concerned that I'm going to break something if put more torque on the nut. With that in mind I'm about to disconnect the complete blower and squirrel cage from the burner in order to be able to get access. Is this necessary or am I going down the wrong rabbit hole? From your earlier response it sounds like it shouldn't be such an involved process to get to the igniter.
Our situation is getting a bit urgent since we pulled this Alpine 3555 up an extremely challenging road to live in while we build our home off grid, forecast is for freezing temps this next week and I'm starting to wonder if I'll be able to fix it before the weather closes in. Not possible to move the coach at this time.
Photos are of what I believe is access hatch and gas line from valve up to hatch. More photos easily provided.
Many thanks,
Steen

Roulotte · 10-21-2023, 12:15 PM

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**chuckster57** · 10-21-2023, 01:05 PM

The tube attached to the gas valve will come apart. You need to use a wrench to hold the gas valve assembly while loosening the nut. They are TIGHT.

**chuckster57** · 10-21-2023, 01:14 PM

See if this helps:

http://techsupport.pdxrvwholesale.co...ing-Manual.pdf

Ddaddyo · 10-22-2023, 07:21 AM

Sail Switch.

**chuckster57** · 10-22-2023, 07:23 AM

Quote:

Originally Posted by Ddaddyo

Sail Switch.

Cant be if it get to ignition point.

Roulotte · 10-22-2023, 08:22 AM

Decided to disassemble squirrel cage shroud enough to be able to get a wrench on the gas valve body. Got gas line to combustion chamber disconnected and hatch off, so now can see diffuser and igniter. Diffuser had a lot of detritus and possibly corrosion on it; used stainless wire brush to clean diffuser. Put pieces back together and reconnected wires. Used car battery as power source.

Flipped the rocker switch, the fan came on, but that was it, no click from the gas valve (which had happened before disassembly) and no ignition sparking at igniter. The fan ran for less than a minute and then shut off.

Plan is to now go through each electrical connection and apply dielectric grease to increase connection integrity. Past that, I guess the next steps may be to start replacing parts, e.g.: sail switch, gas valve, igniter.....
Any and all guidance is sincerely welcomed. Thanks

**chuckster57** · 10-22-2023, 08:25 AM

Was the battery FULLY charged? it takes a good battery to spin the fan enough for the sail switch to make contact. We use a battery hooked up to a charger.

Roulotte · 10-22-2023, 08:35 AM

Good morning, actually used jumper cables from battery of running vehicle.

**chuckster57** · 10-22-2023, 08:39 AM

Do you have or can you get a test light? You can verify voltage at each step to rule out a component. You can also jumper the sail switch to rule it out.

Roulotte · 10-22-2023, 11:01 AM

Thank you very much. We are going to go through each connection focusing on the gas valve and igniter along with the sail switch using multimeter with needle probe.

jancoe1 · 10-22-2023, 05:19 PM

When furnace calls for heat. Power will go through the limit switch and to the sail switch, then to board. If board sees power from both, the board will allow the gas valve to open and ignition to take place. You do not need lp hooked up to get the furnace to go through its steps of operation. Obviously without gas no fire. When I tear down a suburban I use a 5/8 crowsfoot wrench so you don't have to disassemble the blower assy. When opening up access to the burner, the electrode gap should be 1/8 on top of the burner. There is procedures you can find on gap location/placement. I typically use a 1/8 drill bit to check gap. These are very simple furnaces and usually the main problem with suburban is the electrode gap will typically grow/open away from the burner and cause a failure to ignite after years of service. Also, dont forget to remove the gas orfice and check if any debris is blocking the flow of gas.

jancoe1 · 10-22-2023, 05:26 PM

The white plug on the circuit board. When attempting to run the furnace, check the red wire to see if you have 12 volts. If you do, the limit switch and sail switch are working.

Roulotte · 10-23-2023, 12:50 PM

Thanks a lot for this. Everything works up to point of ignition. I didn't see your advice on the igniter gap before I reinstalled: we were getting sparking so thought we would get ignition but that didn't happen when I put everything back together. So will disassemble again and check/adjust igniter gap. I thought the sparking looked weak but was advised that it would enough to ignite the gas. Your advice is really helpful as I am a total novice at this.

Roulotte · 11-06-2023, 08:15 AM

I wanted to thank all of you who sent us very valuable input and advice. My husband spent almost a week fixing the goshdarned thing and was able to do so thanks to everyone's advice on this thread.

The furnace is now working, however, it takes at least two times before it ignites properly, not sure why that is and we end up "banging" on the exterior exhaust in order for it to ignite. Any ideas?

Camping family · 11-06-2023, 10:18 AM

Quote:

Originally Posted by Roulotte

I wanted to thank all of you who sent us very valuable input and advice. My husband spent almost a week fixing the goshdarned thing and was able to do so thanks to everyone's advice on this thread.

The furnace is now working, however, it takes at least two times before it ignites properly, not sure why that is and we end up "banging" on the exterior exhaust in order for it to ignite. Any ideas?

Can you provide what your problem was and what he did to fix it.

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