Furnace won't light

I would check the sail switch first. It could have a small speck of dirt preventing it from lighting. Blow furnace out with some canned air spraying around the sail switch good.
I am guessing that the fan starts, is this correct?
What is make and model of the furnace?

enblethen wrote:
I would check the sail switch first. It could have a small speck of dirt preventing it from lighting. Blow furnace out with some canned air spraying around the sail switch good.
I am guessing that the fan starts, is this correct?
What is make and model of the furnace?

Yes the fan runs. Whats the sail switch? Its a suburban I think. Model info will follow when I get home in about 30 minutes

The sail switch is a metal flapper in the blower outlet that is connected to a microswitch. If there is not enough air flow (maybe a low battery and not letting the blower come up to speed) that will close and allow the furnace to proceed to the lighting sequence.

You need to check your battery voltage at the furnace.

Ken

I'll try it with the genny running but I keep the battteries on a tender so they should be good. I havent used the trailer since spring but it stays in my garage and I run the genny periodically and then put the battery tender back on. What should voltage be at furnace and where check it?

It was low battery. Barely could start genny.

I guess my battery tender wasn't keeping the batteries charged. Its a Battery Tender Plus. Perhaps it thinks the batteries are charged when in reality, because they are deep cycle batteries, they run way down before the tender thinks they need to be charged?

I've noticed if I disconnect it and reconnect it, it will charge for days before it thinks they're fully charged. The trailer has been disconnected for a couple weeks on top of the tender not being in charge mode for a while.

Glad you found your problem!
I would locate the model and download the manual. It will help later if other problems arise. There should be a pats break down which will show the sail switch. Many times that can be an issue.

enblethen wrote:
Glad you found your problem!
I would locate the model and download the manual. It will help later if other problems arise. There should be a pats break down which will show the sail switch. Many times that can be an issue.

Good tip. Thanks. Will do. I've got the install instructions, but it covers multiple models. After it fired up, I forgot to note the model.

Thanks again guys!
Dave

You may want to down load the manuals for other troublesome appliances like the water heater and the refer.
It is good to have the exact make and model along with the serial number. When appliances fail, it is cold, raining and dark. Much easier to look up problem inside where it is dry, you have some light and hopefully a little heat.