Furnace fan runs - no heat

AndrewC · 01-02-2021, 09:51 AM

We have been using our furnace for a while now in our 2021 Eagle. A few days ago, I turned on the heat and went back to whatever I was doing. A while later I realized it hadn't warmed up. I went back to the control pad and it shows it was on and set to 70 degrees. But the temp had dropped another 3 degrees instead of going up to 70. I turned it off and then back on. I stood over the vent and felt cold air for about 5 minutes or so and then it just shut off. No heat. I checked our propane takes and they are good. We can use the stove so there's propane and it's flowing. I checked the fuses and the furnace fuse is fine. I can't get to the furnace as it is buried under the bathroom behind the wall on the other side of the water heater. Of course it's under warranty but we live in it so taking it to a dealership isn't a simple matter, not to mention they are all booked out for weeks or months. Right now we are running several space heaters but the electric bill is going to kill us doing this. Anyone else have this problem?

CAG · 01-02-2021, 10:47 AM

Call Jayco and see if you can get permission to use a mobile repair service. Likely if they ok it you will have to pay the response charge and that Jayco will reimburse rather than cover by paying the repair shop.

Also consider that the warranty is from the furnace manufacturer and not Jayco so you can also try contacting the manufacturer to see if they would cover a mobile repair but again, you pay the shops response fee.

Duke4857 · 01-02-2021, 11:20 AM

First make sure you have enough battery power to run the furnace. If the fan does not spin fast enough the sail switch will not let the gas turn on.

Ours has done the same thing 3 times. In my experience the sail switch in the furnace bends/fails and will not let the gas turn on. The fan times out and turns off the furnace. I have to completely remove the furnace to get to the sail switch. Not a easy task, it takes me several hours to it fixed. If it is under warranty figure out how to have them fix the trouble. Ours went out of warranty a year after the first fix.

The furnace is the only major thing on the TT that we have had trouble with.

AndrewC · 01-10-2021, 02:42 PM

Well I got under there and managed to get the furnace turned around to get to the sail switch. The paddle on the switch was nice and flat. I could hear it click when i toggle the paddle back and forth. Being brand new I don't suspect it's dirty. Interestingly this model of sail switch is no longer in production. Supposedly there's a replacement but I'll be darned if I can find the right part. All the others appear to be a bent design which I'm not sure will work on this furnace. What's crazy is the serial number on the furnace isn't ANYTHING like the serial numbers listed on the parts sites. For my furnace model (FMD35121) there's two different switches based on the serial number. But my serial number starts with 011 I think and the listed serial numbers start with 724...

So I tried to bend the paddle a little and put it back in. I turned the furnace back on and I could hear the fan run and then I could hear it trying to fire but in spurts. It would fire for a second or two and then go out. Just did that over and over again until I killed the furnace by pulling the fuse.

ALJO · 01-10-2021, 04:52 PM

You still might have to adjust the flame sense position, which might have been the cause in the first place. Nevertheless adjusting the sail-switch for better lift is a good idea.

AndrewC · 01-10-2021, 04:54 PM

Quote:

Originally Posted by ALJO

You still might have to adjust the flame sense position, which might have been the cause in the first place. Nevertheless adjusting the sail-switch for better lift is a good idea.

Any idea how to adjust the flame sense position? Is that something that would have somehow been messed up just by running the furnace? It used to work. Worked fine for the last couple months. Then suddenly stopped working.

ALJO · 01-10-2021, 05:04 PM

These furnaces are always in awkward places to work on, we always remove them for bench-testing, because at least we can check all options and start-run-stop them many times. Sometimes the burner air-intake may cause the flame sense to malfunction, sometimes it is the flame-sense itself, other times it is the propane flow. Even the electronic need all the functions working.
What is your flashing code?

AndrewC · 01-10-2021, 05:07 PM

I saw a single flash of red between two of the connectors on the board. But couldn't spot the light itself due to the location and angle. The sticker on the fan says that it should be a single flash with 3 second delay. But it would flash and then nothing for a while. Then it would try to ignite again and gave me the one flash. Did that a few times then stopped giving me any lights at all but fan kept running.

theracqueteer · 01-10-2021, 06:08 PM

Quote:

Originally Posted by AndrewC

We have been using our furnace for a while now in our 2021 Eagle. A few days ago, I turned on the heat and went back to whatever I was doing. A while later I realized it hadn't warmed up. I went back to the control pad and it shows it was on and set to 70 degrees. But the temp had dropped another 3 degrees instead of going up to 70. I turned it off and then back on. I stood over the vent and felt cold air for about 5 minutes or so and then it just shut off. No heat. I checked our propane takes and they are good. We can use the stove so there's propane and it's flowing. I checked the fuses and the furnace fuse is fine. I can't get to the furnace as it is buried under the bathroom behind the wall on the other side of the water heater. Of course it's under warranty but we live in it so taking it to a dealership isn't a simple matter, not to mention they are all booked out for weeks or months. Right now we are running several space heaters but the electric bill is going to kill us doing this. Anyone else have this problem?

Are all your other LP appliances working? Stove will still light with a bad regulator which is supplying LP at too low a pressure for appliance to run.

AndrewC · 01-10-2021, 06:14 PM

Water heater and stove both work. The fridge worked fine on LP that last time we lost power to the resort here but that was before the furnace stopped working.

I have noticed that there's a bit of a propane leak when I don't have one of the cans connected. On the driver side there's the can and the regulator with the toggle between cans. The passenger side has just a regular regulator. When I disconnect the passenger can and have the driver side connected, on and the regulator switched to the driver side can, we still get a bit of propane leakage. I have to keep the propane hatch door open on the passenger side when it's not connected because we get that smell leaking up into the rig. When the passenger side can is empty, I just close it and leave the hose connected to avoid the leakage.

I don't know that this makes a difference for the furnace as this has been the case for a while. Also, as I said the other appliances still work on propane while on the one can on the driver side.

CAG · 01-10-2021, 06:51 PM

Bottom line with this is you need to get someone out to look at it. Propane leaks are dangerous.

AndrewC · 01-10-2021, 06:56 PM

Quote:

Originally Posted by CAG

Bottom line with this is you need to get someone out to look at it. Propane leaks are dangerous.

Agreed. But it's not exactly a leak so much as the regulator on the driver side is still allowing backflow of propane to go back through to the other side of the rig to the can that supposed to be connected. If I have to remove that can I just turn off the can on the driver side to avoid that. But it makes me wonder if the regulator is bad or if that is just normal for those things.

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