So, I've encountered an issue that I can't resolve and wanted to see if there are any troubleshooting steps I've missed before bringing it in to the dealer.
Today, our furnace stopped working. Yesterday it stopped for a bit, but I fixed it by switching over to the fresh propane tank (even though we have an auto switchover and the old tank does have some propane left in it). So I thought maybe it was some weird propane issue, but, today, even with the ~75% full tank selected, the furnace will not turn on. The gas cooktop lights without any issue.
A few details:
We have a 2024 Trade Wind 25FB.
We are using the MicroAir Smart Thermostat with gas override turned on.
We have GasStop emergency shut off valves on the tanks.
We are plugged into 30 Amp power and batteries are at 100%. Voltage looks fine, no issues with the 12V system as far as I can tell.
We have a Dometic furnace (not entirely sure which model, our manual is for the DF series with a bunch of model names on the front).
Exterior temps about 40 degrees (down below freezing at night)
Thermostat set to 68 (also tried 72, 75, and 85), interior temps in the 50s.
Here are the troubleshooting steps I've tried to far:
Turn everything off and then turn it on to furnace. Fans run for a few seconds, then shut off. Furnace never fires. Did this a dozen times, including at least 3 times back to back after running the stove to ensure no air in the propane lines.
Turn propane tanks off, disconnect, wait a minute, reconnect, prime GasStop, and try again. Same result as above.
Ran the stove top for about 10 minutes to be sure there was no air in the gas lines.
Set to heat pump (heat pump works fine, it's hovering around 40 degrees outside, and so far the gas override has not kicked on).
Turn off the gas override and try the first step again.
Checked the fuse panel (furnace fuse is fine)
Checked the intake vent and all the output vents for obstructions (none found)
Anything I missed? Any suggestions? If we can't resolve it on our own, it probably means we need to cancel our trip next week.
hikingcamera, one common heater problem is the sail switch. The purpose of the switch is to sense airflow from the fan before it turns on the gas valve.
From your description, fan runs for a short period of time then shuts off, that would match the behavior of a failed (or stuck/dirty) sail switch.
You can access it from the outside. The switch has a paddle on it that moves when the fan is on. When the switch closes, the system will open the gas valve and ignite. You can remove the switch and test it with a continuity meter.
Also, check to see if you can feel it “click” while holding it and moving the sail. See if there’s anything on the switch or inside the housing that would interfere with it’s movement.
I replaced mine at home as a preventive measure and kept the original as a spare.
You can access it from the outside. The switch has a paddle on it that moves when the fan is on. When the switch closes, the system will open the gas valve and ignite.
Thank you! I forgot to mention in my post that I am pretty sure I know where the furnace is, but was not entirely sure how to access it. On the outside, it's an inlet port and a metal panel of some type, so you're suggesting that I should be able to open that, right? Any tips on how? I wasn't certain. It looks like I have to unscrew the panel. Just didn't want to dive into something without a sense of the level of complication.
I had the same situation. I heard about a possibly dirty sail switch. I watched some videos and then took out the sail switch, removed a little piece of lint and then reinstalled it. The furnace worked afterwards!
2023 25' Globetrotter
2021 16' Bambi
Forest Lake
, Minnesota
Join Date: Mar 2021
Posts: 1,928
I've had many a furnace adventure with our 2023.
The furnace cover can be a bit sticky, so you might have to pry it off. Note if there is a red light flashing and the number of flashes. Flashes at least mean the board is getting power. One every few seconds and I think that's indicative of the sail switch. You can try the reset switch also.
The first time ours went out very similar to your symptoms - fan came on then it switched off. I tried everything including replacing the thermostat, sail switch, board. JC repaired it and they said it was the regulator.
It worked in the spring but then last fall it went out again. This time I replaced the sail switch again and it started up. I couldn't find anything wrong with the sail switch, maybe it was the connection, so wiggle some wires too. Here's a link to sail switches for our unit.
Not sure if / and or when Airstream did [ did not on earlier models - mines an 85 ] --- if they have a screen on the outside intake & exhaust --- almost never see this .
What happens a LOT --- is bugs get inside to make a nest & blog the sail switch from moving .
A couple of decades ago when I saw this for the first time , I got some stainless screen and put in place [ your type of outside IN & EX , differs from mine .
Many other manufactures of RV do have these screens ???
__________________
85 Excella , 31' , electric brakes , R. twin [ would like it to be a single ] , future upgrades , composting toilet [ replace black water tank with a 2nd fresh ] , solar power , instant hot water heater .
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Okay, an update. I got into the furnace compartment, and did a few things:
Pulled the sail switch, found a barely perceptible amount of lint or something on it, but looked fine and moved freely otherwise.
Turned the furnace switch off, waited for 10 seconds, and then turned it back to "reset." Did this three times for good measure.
Turned the furnace on and looked for the lights on the circuit board. It was flashing once every 3 seconds or so, which in my manual is listed as "Limit Switch / Airflow Problems" (page also included below). Left it on for half an hour or so and it continued to flash the same pattern.
From the pictures, is it still possible something is wrong with the sail switch? And does anyone know from the picture what sail switch to replace it with? It's been on my list to carry a backup of that but am not certain which one. It's possibly the same as the one I see linked in a comment above, but I'm not certain.
2023 25' Globetrotter
2021 16' Bambi
Forest Lake
, Minnesota
Join Date: Mar 2021
Posts: 1,928
I'd just order a new sail switch and see. Like I said I couldn't find anything wrong with ours but replacing it worked. I'm 99% sure the link I posted is the correct sail switch, looks identical to ours. Here's the model number etc.:
Okay, an update. I got into the furnace compartment, and did a few things:
Pulled the sail switch, found a barely perceptible amount of lint or something on it, but looked fine and moved freely otherwise.
Turned the furnace switch off, waited for 10 seconds, and then turned it back to "reset." Did this three times for good measure.
Turned the furnace on and looked for the lights on the circuit board. It was flashing once every 3 seconds or so, which in my manual is listed as "Limit Switch / Airflow Problems" (page also included below). Left it on for half an hour or so and it continued to flash the same pattern.
From the pictures, is it still possible something is wrong with the sail switch? And does anyone know from the picture what sail switch to replace it with? It's been on my list to carry a backup of that but am not certain which one. It's possibly the same as the one I see linked in a comment above, but I'm not certain.
Hikingcamera, do you have access to a Volt-Ohm meter? If so, remove the two blue wires from the sail switch, connect one lead to each contact on the switch. With the meter set to ohms, actuate the switch. It should go to zero when the switch is closed.
If you don’t have a meter, as a test, connect the two wires together (jump them) and cycle the furnace. NOTE: This is just a troubleshooting step, never leave it jumped in normal use. If the furnace runs as expected, replace the switch. If not, there’s another problem.
Hikingcamera, do you have access to a Volt-Ohm meter? If so, remove the two blue wires from the sail switch, connect one lead to each contact on the switch. With the meter set to ohms, actuate the switch. It should go to zero when the switch is closed.
If you don’t have a meter, as a test, connect the two wires together (jump them) and cycle the furnace. NOTE: This is just a troubleshooting step, never leave it jumped in normal use. If the furnace runs as expected, replace the switch. If not, there’s another problem.
I do have a simply multimeter with an ohms setting. It doesn't have clamps, just the little metal poker thingies (not sure of the technical term), so may require some creativity to get everything to stay connected to run the test. I've been meaning to get a better multimeter.
Sometimes you can hold the probes in one hand like chop sticks and actuate the switch with the other.
Before you do, set the meter to a low ohms scale and touch the leads together. The meter should go to zero. Go ahead and test the switch if the meter works.
Sometimes you can hold the probes in one hand like chop sticks and actuate the switch with the other.
I'm just not sure how to keep the wires attached to the multimeter if I disconnect them and they are dangling free. But I could probably hold the wires in one hand, the probes in the other, and then switch it on with a pinky or something. I'm sure I'll figure it out.
One note, there are three wires going to the sail switch. Though two seem connected together to the same clamp.
I'm just not sure how to keep the wires attached to the multimeter if I disconnect them and they are dangling free. But I could probably hold the wires in one hand, the probes in the other, and then switch it on with a pinky or something. I'm sure I'll figure it out.
One note, there are three wires going to the sail switch. Though two seem connected together to the same clamp.
Hopefully I can give that a test tomorrow.
That is to test the switch no need to touch the wires or be anywhere near the trailer, you can take the switch and meter and find someone to hold and activate switch while you use the meter on the contacts.
2023 25' Globetrotter
2021 16' Bambi
Forest Lake
, Minnesota
Join Date: Mar 2021
Posts: 1,928
Just a data point, when I took my sail switch out and tested it with a multimeter, it passed. The new one I put in worked, so I don't know if it was the leads or maybe the paddle wasn't engaging the switch contacts or something. I think jumpering the sail switch connectors to see if that is the issue might be the best approach.
Ah, ahem... I apparently need to work on my reading for details skills. I misread the original comment and thought the suggestion was to test the wires rather than the leads on the sail switch itself. I know how to use my multimeter, I was just uncertain how I was going to hold 3 wire ends and two multimeter leads against each other.
I'll do some further testing. In the meantime I have an appointment with me dealer on the calendar if I end up needing it. And they were going to get back to me about locating the "limiter switch" that the manual refers to which they have said is different than the sail switch. I'm just not certain where the limiter switch is. But I've got new sail switches arriving today, so I can at least try to rule that out as the culprit.
There's the high temp limit switch. I got one of those off Amazon too, but never did replace it. I have it just in case.
Okay, learned some more! So that is what the third wire on the sail switch. There must have been some lost communication because my dealer said I could look to see if there was some blockage there, but I was talking to the service advisor who was relaying what the service tech team told her, so it's not uncommon for the technical details to get lost in the translation. (Don't get me wrong, she does a good job at what she does, which is getting folks into service and communicating the issues to the techs accurately so they can address them).
Regardless, I ended up replacing the sail switch with the ones that arrived today, and we're back up and running! I'm happy I was able to figure it out. Would have spent more in gas than I did on the sail switch, and I would have lost hours of time (our nearest dealer is an hour away).
I couldn't get either sail switch to fire anything up on my multimeter. As I said, it's a cheapo, no batteries, so I think with the cables removed and no power running through the switch, the multimeter won't even turn on. Or maybe I just wasn't choosing the right sensitivity. It's on my list to get a better multimeter.
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I know how to use my multimeter, I was just uncertain how I was going to hold 3 wire ends and two multimeter leads against each other.
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