Furnace doesn't always light

Old-Biscuit wrote:
Here is a generic troubleshooting guide........LINK

It covers Atwood.........but Suburban aren't different in how they work (just design).

Not only are they "Not different" in how they work.

If you go to the Dinosaur Board web site, you will find that a good number of Surburans, and Atwoods, take the very same control board.

My FAN-50+ fits several models in both lines.

Pulled the cover off and the sail switch moves freely flips the switch easily. The only thing I found is that the connector on the red wire that connects to the cylindrical ignition coil? seemed a bit loose. I closed the connector a bit and pushed it back on. We'll see if that makes a difference. At least the furnace ran one for one attempt after reassembly.

I hope it keeps working because we're facing some very cold weather (for the south) for the next few days.

The furnace is an Atwood 8940-III DCLP. I have the manual now so I'll take off the cover from the fan to check out the sail switch. Pulling the exterior cover off showed no dirt or damage. The problem shows up equally whether or not on shore power.

I would check the burner tube to see if might be a little blocked or rusty. It doesn't take much. Probably just needs a little preventative maintenance done. Might have a spider or insect nest in there too.

Hi All.

When was the last time you did "Proventave Maintance" On all of your RV's Equipment. They all need cleaning, from time to time. Or you will for sure have problems sooner or later

Take good care of your RV, and your RV will take god care of you.

Good Luck. Happy Travels. Dan & Jill & our 2 Kid Yorkies

Here is a generic troubleshooting guide........LINK

It covers Atwood.........but Suburban aren't different in how they work (just design).

With fan blower coming on...thermostat is working
With it not lighting.....no spark no main flame then the first thing in line is 'sail switch'
It has to make up before power can be applied to control board for spark/main flame

Low 12V DC voltage will cause fan blower to NOT come up to proper speed therefore not enough air flow to move the paddle on sail switch and make it up.
Also just a dirty sticking sail switch will cause same problem

Here are specific service manuals for:
Atwood......LINK
Suburban....LINK

If you are not hooked to shore power check your battery voltage.

You are not the brand or type of furnace. Does it just work on propane or electric also. If it is a Suburban there is plenty of information available on the 'net. Check to be sure there are no obstructions in the tube. Is your igniter (sp) ok at the end of the burner. Check for webs or other obstructions in the chamber. If it is ignighting and then going out then you probably have 12V going to it.

If the furnace doesnt even attempt to light (igniter not clicking) I would think it is probably because the sail switch is not moving properly and the system has a safety so it would not attempt to light until fumes from previous attempts is evacuated. Cleaning is probably all it needs.