Furnace issue - fault circuit board?

[vossom]

In my 2016 28A Flying Cloud I started having furnace troubles yesterday. When activated by the thermostat, the blower comes on as usual and then shortly after the furnace ignites, but it only stays lit for about 6 seconds. 10-15 seconds goes by and the furnace ignites again and again only stays lit for 6 seconds. And then again one final time until the system shuts off. Hot air blows out of the exhaust vent when the furnace is lit and I can smell the propane odor and hear it flowing through out of the tanks.

I've already read through every thread I could find on this and tried all the suggestions. Cycling the whole system, checking other LP appliances, switching to a full tank, clearing the lines and turning on the tank very slowly, restarting multiple times, checking battery voltage, all with the same result. The LED on the ignitor board is blinking 3 times indicating ignition failure.

The furnace has been in regular use for the past few weeks as I've set the thermostat to 45 since I haven't winterized yet and there have been a few nights in the 30s here, and some nights I go out there for an hour or so just to hang out, and turn it up to 65. Haven't had a single issue before.

It seems the most common fix is replacing the ignitor board but is it really that likely that the ignitor board is already done for on a 2016 trailer which I've owned for 3 months? I could probably bring this in to the dealer but I can't wait (trip coming up), don't want to have to take the time to drop it off and pick it up, and I'd like to learn how to do more myself.

A final piece of information, I did actually start winterizing my trailer yesterday, so maybe I did something to break the furnace? I can't imagine what, all I did was drain the hot water tank and blow the water lines with air.

Thanks in advance for any help or suggestions.

Jason

[GCinSC2]

Jason,

Not sure if my '07 furnace and your '16 have this in common but easy to check. Look at your troubleshooting section of the furnace owners manual. Does it have a fault light? Mine does, little blinking light. That might give a clue.

On mine I was troubled by an electrical running tap connection. They used a tap connection onto a wire and it just didn't make a solid connection plus a bit of corrosion. I flicked the tap and got a response, replaced inline with full crimp connection and that was that.

[ShinyPete]

Well...... I'm just spitballing here but I'll give it a shot.

First thing I would check is voltage. Is it possible that your batteries are not fully charged? Perhaps you hit the store switch by accident or you're not connected to shore power? Low voltage can do really weird things especially with the furnace operating fine until your winterization project.

The only other thing I would think is the control board as you mentioned or perhaps a "burn sensor" like on the fridge gas section? Something is telling the unit to shut down as soon as it fires obviously.

Hope this helps.

On edit - I went and pulled the cover on ours two screws and the metal exterior cover flips down and then you can flip down the plastic interior cover. I don't have any great advice here but perhaps check all your wiring connections with an insulated pair of needle nose pliers. A wire could have popped loose, there's a lot of push on connections in there.

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[crisen]

We have this issue about once a year. I use air compressor and vacuum to clean out blower and cold air return and this has always got it going. I assume sail switch is hung up. In our case probably due to pet hair getting into system or dust from gravel roads.

[vossom]

Originally Posted by GCinSC2

Jason,

Not sure if my '07 furnace and your '16 have this in common but easy to check. Look at your troubleshooting section of the furnace owners manual. Does it have a fault light? Mine does, little blinking light. That might give a clue.

On mine I was troubled by an electrical running tap connection. They used a tap connection onto a wire and it just didn't make a solid connection plus a bit of corrosion. I flicked the tap and got a response, replaced inline with full crimp connection and that was that.

Yes the light is blinking 3 times which indicates ignition failure. Maybe I will try playing with the connections a bit maybe something is loose but didn't seem so. Thanks.

[vossom]

Originally Posted by ShinyPete

Well...... I'm just spitballing here but I'll give it a shot.

First thing I would check is voltage. Is it possible that your batteries are not fully charged? Perhaps you hit the store switch by accident or you're not connected to shore power? Low voltage can do really weird things especially with the furnace operating fine until your winterization project.

The only other thing I would think is the control board as you mentioned or perhaps a "burn sensor" like on the fridge gas section? Something is telling the unit to shut down as soon as it fires obviously.

Hope this helps.

On edit - I went and pulled the cover on ours two screws and the metal exterior cover flips down and then you can flip down the plastic interior cover. I don't have any great advice here but perhaps check all your wiring connections with an insulated pair of needle nose pliers. A wire could have popped loose, there's a lot of push on connections in there.

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Voltage is good, connected to 20A, also tried on batteries when voltmeter read 12.5. I will check on the wiring. If nothing else I will buy a new board and if that doesn't work I'll have to find a mechanic. Thanks

[vossom]

Originally Posted by crisen

We have this issue about once a year. I use air compressor and vacuum to clean out blower and cold air return and this has always got it going. I assume sail switch is hung up. In our case probably due to pet hair getting into system or dust from gravel roads.

From what I understand if the sail switch is hung up then the furnace won't ignite at all. I've only had the trailer for 3 months and only taken 2 short trips with no pets, so I can't imagine anything being clogged up or too dirty. If the system were that sensitive I'd imagine this problem would be more widespread but hey you never know. Thanks for the suggestion

[crisen]

I can only tell you that ours has identical symptoms, heat out furnace exhaust and light blinking 3 times. Cleaning fixes problem. I think if you check furnace troubleshooting list sail switch is on it for 3 lights.

[vossom]

Originally Posted by crisen

I can only tell you that ours has identical symptoms, heat out furnace exhaust and light blinking 3 times. Cleaning fixes problem. I think if you check furnace troubleshooting list sail switch is on it for 3 lights.

The manual indicates Ignition Lockout Fault

Ignition Lockout Fault --- 3-Flashes With 3-Second Pause --- Soft(1 hr retry)

[kenfconnor]

I am far from an expert and don't know that particular furnace but sounds to me that it could be related to thermocouple (is supposed to sense that the flame is on based upon heating up, if flame is not on after a few seconds the controller will shut off the gas to eliminate explosion risk). If this is the case either the thermocouple has gone bad (usually easy and cheap to replace) or it is not connected properly to the controller board. I had a similar issue with my pool heater and found a rodent chewed through the wire from the thermocouple to the control board. Was a simple $15 replacement.

[JCWDCW]

I agree with kenfconner. If it lights then drops out the thermocouple might not be seeing enough flame when it gets running. Flame shape could change or the flame might be fluttering once established. Could also be the probe is opening up as it heats up. Despite no real problems on my furnace flame and thermocouple, the tech changed the igniter/TC assembly when he put in a new board. Try cleaning it with sandpaper or an emery board. The TC probe must be right in the middle of the flame. Adjust it by bending the probe
JCW

[AstroBruce]

Check to make sure you don't have a water leak at the galley sink. It will drip water onto the furnace and circuit board. I had this problem. took me a while to track down. Drenched the board a couple of times. Just blow it off, and it should work.

Bruce

[vossom]

Originally Posted by JCWDCW

I agree with kenfconner. If it lights then drops out the thermocouple might not be seeing enough flame when it gets running. Flame shape could change or the flame might be fluttering once established. Could also be the probe is opening up as it heats up. Despite no real problems on my furnace flame and thermocouple, the tech changed the igniter/TC assembly when he put in a new board. Try cleaning it with sandpaper or an emery board. The TC probe must be right in the middle of the flame. Adjust it by bending the probe
JCW

If it is the thermocouple then I am not sure I would be comfortable changing this out myself, right now I have on idea where this even is

[vossom]

Originally Posted by AstroBruce

Check to make sure you don't have a water leak at the galley sink. It will drip water onto the furnace and circuit board. I had this problem. took me a while to track down. Drenched the board a couple of times. Just blow it off, and it should work.

Bruce

Thanks, this is a possibility. As mentioned in my OP, on the day of the issue I was winterizing the trailer. When I disconnected the water filter at the galley water I made a bit of a mess.

I will try blowing the board and reseating all the connections.

[vossom]

Originally Posted by AstroBruce

Check to make sure you don't have a water leak at the galley sink. It will drip water onto the furnace and circuit board. I had this problem. took me a while to track down. Drenched the board a couple of times. Just blow it off, and it should work.

Bruce

This was it. Pulled the board out to blow it off with compressed air and found some water underneath. Blew it all dry, made sure all connections were seated properly, and voila, heat.

Thanks Bruce!!

This was indeed my own fault as I spilled water everywhere under the sink when removing the galley filter, and as I learned during this whole process, the furnace is directly under the sink cabinet, which is where the water spilled.

So no harm done, hopefully. On the upside I learned a great deal about my furnace system and what NOT to do when winterizing. Learning a lot lately

[AstroBruce]

Glad it worked out for you.

Bruce

[GCinSC2]

And Paul Harvey always says:

And now the rest of the story.

But I didn't see that one coming.

[mefly2]

We had similar symptoms ...turned out to be the high limit switch. Glad yours was an easier fix.

[BAB]

...My furnace is also located directly under the sink. Given the proximity to both hot and cold water right next to it, as well as a sink directly above it, I think I'll come up with some kind of system to do some "water resistance proofing" above the furnace and below all this water. Oh, and the hot water heater is also located right under the lavatory sink. Will check that out as well.