Furnace troubleshooting

[RobertRand]

Hello all, I'm in need of some troubleshooting tips for my Atwood 8500 series furnace.

My furnace has stopped lighting. The fan will run for a minute or so, the furnace will not light, and then of course the fan stops. I think I'm getting gas, well not me, but the furnace, because the hot water tank works on gas the way it should. I have checked for voltage at the heater, and I have voltage. I did recently have a gas regulator issue, the hoses were leaking so I replaced them, and I did lose the little plastic ball in the switcher. But as I said, the hot water tank works, and the range works.

Any ideas or troubleshooting tips would be appreciate, we keep the RV warm with space heaters, but it has cost us a bunch.

[Arch Hoagland]

Did you check the sail switch?

When the blower starts there is a little switch with a blade on it to detect that air is moving. If that switch doesn't close then the gas won't light.

The switch is in the air return part of the furnace.

[firedoc]

If you can hear the furnace clicking (electronic ignition) but does not light and fan stops, it is not the sail switch. If fan runs but no clicking it is most likely the sail switch.
Hope that helps.

[Jay D.]

I had the same problem. so when I got poking around and touched a certain wire it started. wire terminals look good and clean but loose contact were they slide together unplug and replug or clean with some kind of contact cleaner .
Jay D.

[keymastr]

Try closing the valve at the bottle with the stove on then turn stove off after it goes out. Then turn the valve on the bottle on again VERY SLOWLY.

[edge68474]

I have the same furnace, same problem. Ended up being the sail switch.

[60sumtin]

Hi Robert and welcome to iRV2.

Lots of good information given. I'll share with you what had happened to our furnace one time. You didn't mention whether or not you can hear it clicking while the furnace tries to ignite. If you can hear it, it may be due to the electrodes not being the right distance apart. The last trailer I had developed that issue and found the electrodes were too close together to provide a good enough spark to ignite the gas. The gap was widened a bit to provide a bigger spark and it worked fine after that. Just something else to check. Cheers.

[allenb12]

Mine was acting the same way. Turned out a small bug had stopped up the orifice.

[RobertRand]

Originally Posted by firedoc

If you can hear the furnace clicking (electronic ignition) but does not light and fan stops, it is not the sail switch. If fan runs but no clicking it is most likely the sail switch.
Hope that helps.

I can't hear any clicking, the fan runs, then shuts off when it doesn't start.

[RobertRand]

Originally Posted by 60sumtin

Hi Robert and welcome to iRV2.

Lots of good information given. I'll share with you what had happened to our furnace one time. You didn't mention whether or not you can hear it clicking while the furnace tries to ignite. If you can hear it, it may be due to the electrodes not being the right distance apart. The last trailer I had developed that issue and found the electrodes were too close together to provide a good enough spark to ignite the gas. The gap was widened a bit to provide a bigger spark and it worked fine after that. Just something else to check. Cheers.

Thanks, and very interesting. I can't hear any clicking at all.

[Jay D.]

Originally Posted by RobertRand

Thanks, and very interesting. I can't hear any clicking at all.

did you check all the connectors in the heater area? have someone turn the heater on then start wigging the wire connectors.
Jay D.

[RobertRand]

Originally Posted by keymastr

Try closing the valve at the bottle with the stove on then turn stove off after it goes out. Then turn the valve on the bottle on again VERY SLOWLY.

That did it! Then when the furnace turned off because it got warm, tried to turn it on again and it wouldn't start.