Furnace ignites, goes out, ignites, out

[Bama]

I have searched the forum and can not find where anyone had the problem I am having with the furnace in my 2018 Eagle 293RKDS.


I turn the furnace on and the blower starts. After a few seconds the burner ignites and goes out in a second or two. The blower stays running then after about 30 seconds the burner ignites and goes out in a second or two. The blower never turns off and the gas never burns longer than two seconds. I have let it run for 15 minutes and it keeps repeating this cycle.

Propane tanks were about 1/2 full so I filled the tanks. That did not change anything. The three burners on the stove all burn blue when on at the same time, so I have good flow of propane.


The furnace has worked fine till now. Anyone had this problem? If so what was the fix. I took the wall down in storage area and found the furnace. They did not leave much room for 6'4" man to work!

[Mopar_Earl]

Thermocouple issue?


Earl

[Bama]

I thought about that or flame sensor. I assume I have to remove the furnace to get to this? No access door on side of camper.

[Mopar_Earl]

If they are like the older furnaces they would still have a thermocouple. Which senses the flame is there.
I believe you have to remove the furnace to service it. I haven't worked on any late model furnaces, so I'm not much of help. The older ones could be serviced to a point without removing or had an exterior access cover. Looking at my 2017 Eagle furnace, doesn't appear to have any service access.


Earl

[GHen]

You said you refilled the tanks, so this may not apply and points to the thermocouple, but, try this:
Turn off both tanks, disconnect to release pressure, reconnect, now SLOWLY turn tanks back on. Bleed air out through stove top burners and then try the furnace again.
I had this exact issue as you describe and it was the auto regulator that switches from empty tank to full. Mine shows green and red, and even with full tanks it was red. Had to release the pressure a couple times before it showed green and then the furnace ran fine. The key is to open tanks slowly.
Just something else quick and cheap to try.

[GHen]

Also, my burners on the stove worked also, but looking closely they were running only ay 25%.

[Bama]

Ghen, I will give that a try. My auto switch over has been green. I’ll try it this evening. Thanks.

[jimr63]

Mine (previous trailer) would do this every year after sitting all winter. I would fix it by cleaning out the spider web or mud dauber nest from the gas tube elbow thingy at the ignitor. Every time it acted this way it was something in that tube. Worth a look...


p.s. Sometimes you could barely see the spider web but it was enough to disturb the gas flow. Seemed like that tube had to be spotless in order for the furnace to light properly.

[hoppers4]

I just had this problem recently. It was a simple matter of removing the furnace cover on the outside, disconnecting and reconnecting the circuit board and every other wire connection I could find. Fixed the problem. The thermocouple sensor is very low voltage and it wouldn't take much resistance in a poor connection for it fail.

[hoppers4]

Also, you have to put the cover back on with the extension tube or the burner won't stay lit. I also discovered this after a bit of troubleshooting. You don't have to put the screws back in, but just install the cover with the extension tube for a quick test.

[Bama]

I disconnected the propane for about ten minutes. Reconnected to propane tanks then very slowly opened the valves. Used stove to bleed air out of the lines. Furnace is still doing the same thing.

I looked in exhaust tube from outside the camper and do not see anything. Since Jayco did not install an outside access door for the furnace, looks like I may have to pull the furnace to check the wires and tubes inside the furnace.

Thanks for all the tips on what to check. I will report back when I find the problem.

[Lowmiler]

Isn’t this the classic symptom of a bad sail switch? Once the furnace does not sense air moving through the duct, it shuts down?

Running for 30 seconds afterwards is the normal cool down program after being in heat mode, I think.

[Bama]

The blower is working fine. I have a lot of cold air coming out of the ducts. In fact the blower never does shut off when the flame goes out. I have let it run for 15 minutes. During this time the blower stays running but the flame goes out with in two seconds of lighting. It will continue lighting the flame every 30 seconds or so but it goes out within two seconds.

[Lowmiler]

Originally Posted by Bama

The blower is working fine. I have a lot of cold air coming out of the ducts. In fact the blower never does shut off when the flame goes out. I have let it run for 15 minutes. During this time the blower stays running but the flame goes out with in two seconds of lighting. It will continue lighting the flame every 30 seconds or so but it goes out within two seconds.

Right, with a bad sail switch the blower can blow, but the furnace doesn't sense it. The shape of the switch catches the air moving through the duct and changes position, which tells the furnace that the blower is working.

On second thought, not sure a bad sail switch would even allow the furnace to ignite. I think it has to be blown into proper position first before the furnace will light off. So if you are sure you are getting ignition, it's probably not the sail switch.

[Bama]

I am getting ignition. I can hear it and feel heat for two seconds at the exhaust port outside the camper. Thanks!

[ALJO]

It ignites but doesn't detect the flame, it means the problem is in the burner area. Since your furnace has no outside access door the furnace has to be removed for bench testing.

[parallax]

I had a very similar problem, it was the thermal switch.. ( looks like a diode inline to 2 connector spades close to flame hole/ circuit card... I made a jumper ( for testing only ).. jumped it then cycled my heater... worked perfectly,, went and got a new thermal switch,, been rock solid ever since. also got a spare one, to keep in the trailer for next time.

[Cosmik Debris]

Just my experience, that the exhaust back pressure is sensitive. Was camping in freezing weather and water line would freeze overnight, so, since the furnace exhaust was right next to the water input, thought I'd lean a sheet of plywood against the fifth wheel so the furnace exhaust would warm the water connection. Wrong. Furnace would fire up, shut down. Over and over. Moved plywood and all was fine.
Just wanted to tell this in case your furnace isn't exhausting clearly.

[wondermn1]

I have a 2016 Jayco Precept 31 Ul and had the same problem it would fire for about 3 seconds and go out over and over again. We froze many nights in the mountains as we traveled . finally a 20.00 Walmart space heater worked like a charm. It took all of 2 years to solve the problem and 3 service centers and hours & hours on the phone with Jayco. They replaced the motherboard 4 times and had to actually leave it at the service e center for 4 months and to no avail. finally after 2 years they sent a new furnace and it appears to work fine now. The company that makes them changed ownership so Jayco finally warranted it along with 20 + other items.
Now the front A/C quit working and they tell me warranty is over so I need to replace it on my own so its back in service and I am waiting for the quote on replacement.
i HOPE YOUR UNDER WARRANTY

[Jmac000]

Originally Posted by wondermn1

Now the front A/C quit working and they tell me warranty is over so I need to replace it on my own so its back in service and I am waiting for the quote on replacement.
i HOPE YOUR UNDER WARRANTY

just because the a/c quit working doesn't necessarily mean you must replace it. there are a lot of things to check before I would even consider replacing it