Jayco furnace doesn't stay lit

[Wilieco]

Hi

I was hoping for some help troubleshooting my furnace. It is an Atwood Mobile model 8531-IV-DCLP in a 2004 Jayco Greyhawk. The furnace spins the fan as normal and then lights as it should. It burns for about 10 seconds and goes out. It relights and burns for another 10 seconds and goes out and then relights a 3rd time burns for 10 seconds or so and then goes out and shuts off and locks out. If I reset the furnace (turn heat off at thermostat and back on) it will repeat this process all over again. Usually on the 3rd time it will fire and burn normally. Sometimes it take 4 or 5 times of resetting it. Sometimes it will just light normal. When I first got the RV it did this and I ran around trying to get advice and it just started working and it worked for 4 trips with no issues. Then while parked at home went out to do some cleaning and went to light the furnace it did it again. I find it odd that it has only did it at home. Since it lights I would assume that the fan, sail switch, and ignitor are all good. I can hear it burn and also went outside and can fell the heat from the exhaust. Seems that furnace is not sensing that it is lit and shuts off. I can't seem to find anything that tells me how the furnace knows if it is lit. Thanks in advance for any help

Walt

[Kirk W]

That is probably the ignition probe failing to sense the heat from combustion. I would replace it as they are available from Amazon and not expensive. 

[Wilieco]

I assume that it would be inside the combustion camber with the ignite and burner

thanks

ww

[Kirk W]

Here is a link to a copy of the Atwood service manual for your furnace. Here is a link to purchase the proper ignition probe for $9.26.

[Dutch_12078]

Before you start throwing parts at it, try pulling off the ignitor wire on the circuit board and reconnecting it a few times to clean up the contacts. The flames sense circuitry works at the millivolt level, and it takes very little corrosion to interfere with it. Since the ignitor is apparently igniting the gas properly, it's likely ok. The ignitor is not usually prone to being intermittent. The circuit board can be intermittent though.

[Wilieco]

I found the ignitor and ordered it. should be here tomorrow. I cleaned up everything on the burner side and put it back together. It fired after the first reset. I didn't think of cleaning the control board side so I will try that tomorrow.

thanks

ww

[Wilieco]

Parts arrived and put in the new ignitor/sensor and it works just fine now.

thanks for all your help

ww

Edited February 3, 2022 by Wilieco

[Kirk W]

Happy to hear you got it and thanks for returning to let us know that it is working.