Suburban Furnace ignites intermittently

[southsaglejim]

I have the Suburban NT-30S in my 32 foot 1987 Excella. Turning the furnace on will not always get it to ignite. I did clean my outside the trailer air intake of two small wasp nests but i doubt they were enough to block air. And I cannot get the blower to run when I turn off off the gas and turning the switch on at the thermostat and setting the temperature high.

Since I did get the furnace to work this morning before turning it off to see if I could cycle it again (it failed to) I do not think its is a gas issue or pressure issue.

Because this problem is intermittent I am soliciting ideas as to what might be the most likely problem.

[AstroBruce]

Check to make sure the circuit board is not getting wet or damp. I had this problem when water was leaking from a faucet connection above the furnace.

Bruce

[HiJoeSilver]

Could be a sticking sail switch.

[southsaglejim]

Originally Posted by HiJoeSilver

Could be a sticking sail switch.

Is the sail switch operational when the gas is off to run the blower to clear the chamber of all gas before turning the gas back on an actuating the thermostat for the ignition cycle?

[HiJoeSilver]

It's supposed to be operational when the fan comes on. The fan blows on it to activate it. Without it the furnace won't ignite and will turn itself off.

When you cycle it does the fan at lest try to start then shut down? If so it may be sail switch. If it doesn't even try anything then it may be a bad circuit board.

If you can take off the front cover to see the circuit board it does flash error lights. Google suburban furnace error codes.
This is a good start:

https://m.youtube.com/watch?v=zdk0OvKISFY

[southsaglejim]

I watched many you tube videos, read my owners manual, and scoured every thread on these air forums and other websites too. I have always believed my problem was the thermostat. So after determining I was going to have to go the the professionals and foot a heavy repair bill, I decided to run a fingernail across the thermostat contacts that are controlled by the on off switch and the temperature setting. Once I did that the furnace system functioned fine. In the investigation process I did examine my burner when lit through the inspection hole and it looked very good.

So I want to thank the contributors and my message is before you start taking things apart with the idea of checking the board or the sail switch take a look at your thermostat contacts and think about whether there is not a good connection due to build up and thus reduced or no connectivity.

So when do I get another rivet?

Thanks to all who replied. I am going to check the furnace again, but I have checked it 3 times since and its working fine. So I will check again tonight and in the morning too. Getting ready for some cool weather camping.

[HiJoeSilver]

Glad it was a simple fix. Good catch before getting a's and elbows deep taking the furnace apart.

Im guessing it was a stand alone thermostat setup with the bimetallic spring.