Dometic furnace

[Zeroprotocol]

We have a 2021 sunset trail 253rb. Over the weekend the furnace wouldn’t ignite. Furnace is under the fridge with no outside access to the front with all the wiring.

I’ve got propane to the stove and water tank which is after the furnace. Everything is working fine there. I’ve got power to it and it’ll run the blower for about 15 seconds then it’ll shut off. I’m leaning towards the sale switch either being faulty or dirty.

Since I have no access from the front if I pull the furnace do I need to disconnect my outside exhaust port? Or does it just slide out?

[Wingerdinger]

Originally Posted by Zeroprotocol

We have a 2021 sunset trail 253rb. Over the weekend the furnace wouldn’t ignite. Furnace is under the fridge with no outside access to the front with all the wiring.

I’ve got propane to the stove and water tank which is after the furnace. Everything is working fine there. I’ve got power to it and it’ll run the blower for about 15 seconds then it’ll shut off. I’m leaning towards the sale switch either being faulty or dirty.
Since I have no access from the front if I pull the furnace do I need to disconnect my outside exhaust port? Or does it just slide out?

There are a number of pretty good YouTube videos on the subject. If you don't hear the distinct 'click' of the gas valve, I would first suspect the sail switch, especially if you have pets (hair).
Any work done on the units with the small exhaust duct requires removal of the furnace from the inside. It's not too tough, except for lying on the floor for us old guys. You can usually leave the exhaust alone, but it's a little tougher lining up the duct on reinstallation.
I would go through troubleshooting first though. You don't want to take it out if you don't have to.

[Zeroprotocol]

Originally Posted by Wingerdinger

There are a number of pretty good YouTube videos on the subject. If you don't hear the distinct 'click' of the gas valve, I would first suspect the sail switch, especially if you have pets (hair).
Any work done on the units with the small exhaust duct requires removal of the furnace from the inside. It's not too tough, except for lying on the floor for us old guys. You can usually leave the exhaust alone, but it's a little tougher lining up the duct on reinstallation.
I would go through troubleshooting first though. You don't want to take it out if you don't have to.

Can’t hear that click sound. I did pull it out and check behind the switch and there was a little bit of pet hair. Put it back together and same issue. I’ve got another sail switch coming since it’s cheaper then taking it to a dealer.

[Wingerdinger]

Originally Posted by Zeroprotocol

Can’t hear that click sound. I did pull it out and check behind the switch and there was a little bit of pet hair. Put it back together and same issue. I’ve got another sail switch coming since it’s cheaper then taking it to a dealer.

You can check the sail switch and also the thermal switch for continuity and proper operation with a meter. They are in series with each other, and the wires are easy to find and access. The Dometic wiring diagram in the service manual is a very useful tool.

[Zeroprotocol]

Replaced the sail switch today and all is working perfectly now. Thanks for the help

[Camping2020]

Can I ask, did you get your sail switch from Amazon or a dealer? Asking because my furnace just started this same problem this weekend. Thanks.

[Zeroprotocol]

Originally Posted by Camping2020

Can I ask, did you get your sail switch from Amazon or a dealer? Asking because my furnace just started this same problem this weekend. Thanks.

I went through a dealer. I’m sure Amazon would work too though. I’m sure someone on there will carry it as well