Suburban NT30SP Furnace issue

[Jketchum80]

Having issue with furnace, it will start up and fan blows but will not ingnite. It will blow cold air until I shut it down. I have researched a bit online and come up with either control board or sail switch. Either way I am going to have to pull it out but just checking to see if anyone else has had the same problem and maybe had some tips or more trouble shooting ideas. Thanks!

[bedrck46]

Would be nice to know what model and year the RV is?

[mike837go]

You are already on the right track.


Good News: The furnace is getting 12VDC and a call for heat.
Good News: The fan is starting up.


Fails to look for:
- Sail moving and sail switch actually closing- Binding or switch replacement, broken wire?
- Igniter arcing - controller board, broken wire
- Propane flowing - gas valves: tank safety, kinked line, appliance valve, solenoid, wiring




Get out the DVM or VOM to check the sail switch. The rest is observations when the unit attempts to function.


Double-check that the propane tank safeties aren't tripped.

[Jketchum80]

Sorry, not sure why that doesnt show up like on yours...

It is a 1989 JayCrane 32 5th wheel

[Jketchum80]

Thanks Mike,
I will have to pull the furnace out to check the sail switch, correct?
As for the propane saftey, are they per appliance or whole RV? My stove and water heater work fine.

[JFlightRisk]

We had a '96 Wilderness that wouldn't fire up, and found a small relay that controlled the gas regulator was stuck. My immediate reaction was give it a small tap with a screwdriver handle, and it DID fire up next time. Then it got replaced. Just something else to look at.

[Jketchum80]

Originally Posted by JFlightRisk

We had a '96 Wilderness that wouldn't fire up, and found a small relay that controlled the gas regulator was stuck. My immediate reaction was give it a small tap with a screwdriver handle, and it DID fire up next time. Then it got replaced. Just something else to look at.

Thanks for the tip! Where about was the relay located on yours?

[JFlightRisk]

Originally Posted by Jketchum80

Thanks for the tip! Where about was the relay located on yours?

It was right on the furnace housing, and visible when you opened up the outside door. It was a long time ago, and can't recall how many wires went to it, but do remember it wasn't very big, and I think it was held on with one screw. If you follow the wires from the gas flow regulator, they should lead you to it.

[JFlightRisk]

Follow up: I think my old TT furnace was different than yours, but if you google "Suburban NT30SP furnace manual", there's one that gives a troubleshooting section that may be of help.

[Jketchum80]

So in the middle of winterizing I decided to just go ahead and pull the furnace out. Everything looks fairly good, not real dirty/dusty, no blockages and the sail switch seems to be functioning. It is somewhat rusty inside and around the igniter housing but the first thing I did when I began troubleshooting was pull out the igniter and clean it off with some sand paper, which didnt help anything. I dont know anything about these furnaces and i really dont want to screw it up more than it is so I may just go drop it at the repair shop and see what they come up with.

[JFlightRisk]

(...snip...)" I may just go drop it at the repair shop and see what they come up with.[/QUOTE]

Not a bad choice, as they'll probably have diagnostic tools, and parts. Keep us posted with what they find.