Furnace will not Ignite

joeclorite · 02-11-2019, 04:35 PM

I have a 2019 2108 DS and I cannot get heat from my Dometic Furnace. I've had it for about 8 months now and the furnace worked fine.

Now the Blower turns on immediately and blows cold air, but after 20 seconds it turns off. The propane tanks appear to be about 1/2 full and the stove lights perfectly but the Furnace will not Ignite.
Before I take it into the Dealer I thought some of you had come across this problem?

Teamfoxy · 02-12-2019, 06:23 AM

One likely cause is something obstructing the airflow in the blower so that the sail switch does not activate. Could be a mud wasp nest or even some leaves. You could try blowing compressed air into exhaust or intake and see if anything comes out.
Second step would be to have someone inside the RV turn the furnace on so you can stand outside and see if you hear clicking. That would be the ignighter trying to light the burner. If you can hear it trying to ignight, but it does not, the problem is likely no gas flow. In adition to the stove, do the water heater and the fridge both work on propane? The appliances are more sensitive to gas pressure than the stove, so if they also don't work it could be a faulty regulator.
Any further trouble shooting will require that you remove the furnace from its housing and disconnecting the gas line. You should be able to download a service manual from Dometic and there are lots of videos on U-Tube that will show you how to disasemble the furnace and trouble shoot it with a multi-meter. If you are not comfortable with doing this yourself, take it to a repair shop.

joeclorite · 02-12-2019, 09:01 AM

Thanks Team Foxy,
The air flow seems strong for that 20 seconds and I usually hear the igniter click from the inside. Now I'm hearing nothing.
Big Bird says he had the same problem when his was new and it was a control board.
Since it's only 8 months old and under a 2 year warranty I'll let the Dealer pull it out and check it.

4x4van · 02-12-2019, 10:45 AM

What's your battery level? A slightly low battery will result in not enough airflow to push the sailswitch.

joeclorite · 02-12-2019, 10:51 AM

I'm on shore power so the battery level should be fully charged.

Teamfoxy · 02-13-2019, 07:07 AM

There are two blower cages operating off the same motor. One circulates the air through the heat exchanger to the coach and the other pushes air through the fire box in the furnace itself. Good flow in the coach does not necessarily mean good flow in the fire box. The control board is a possibility, but if the sail switch is faulty or the air circulation is not sufficient, the gas would not flow and the igniter would not try to fire. Hopefully they fix it promptly under warranty.
The good news is that a control board is about $80 on Amazon and a sail and limit switch are under $10 each. They all just plug in, but you still have to disconnect the gas and pull the furnace to get to them.

joeclorite · 02-13-2019, 08:18 AM

Quote:

Originally Posted by Teamfoxy

There are two blower cages operating off the same motor. One circulates the air through the heat exchanger to the coach and the other pushes air through the fire box in the furnace itself. Good flow in the coach does not necessarily mean good flow in the fire box. The control board is a possibility, but if the sail switch is faulty or the air circulation is not sufficient, the gas would not flow and the igniter would not try to fire. Hopefully they fix it promptly under warranty.
The good news is that a control board is about $80 on Amazon and a sail and limit switch are under $10 each. They all just plug in, but you still have to disconnect the gas and pull the furnace to get to them.

Thanks Team Foxy.
Nothing like a warranty!

I'll post the results so hopefully it will help someone else in the future.

Nicole12hp · 02-14-2019, 04:07 AM

@joeclorite, did you find the issue? It sounds like we are having something similar going on.

-Nicole
27bhss 2019

joeclorite · 02-14-2019, 08:42 AM

Quote:

Originally Posted by Nicole12hp

@joeclorite, did you find the issue? It sounds like we are having something similar going on.

-Nicole
27bhss 2019

Sadly, my dealer says that they cannot look at it until May 4th. Yes, 3 months from now.
I am new to having an RV in for service but the backlog was a surprise to me.
So, as long as I'm not boondocking the electric heater will work until then.
If your's is a 2019 with a Dometic furnace there may end up being an issue with a lot of them though.

luvlabs · 02-14-2019, 08:48 AM

This is a common RV heater problem and is most likely caused by blockage in the air intake tube. Often, wasps will build nests in the tube and the end result is the problem you are having. Check your heater manual for the best way to clean the tube and you should be back in business. If you don't feel like doing it yourself, call a mobile repair guy.

old_engineer · 02-14-2019, 11:45 AM

Quote:

Originally Posted by joeclorite

Sadly, my dealer says that they cannot look at it until May 4th. Yes, 3 months from now.
I am new to having an RV in for service but the backlog was a surprise to me.
So, as long as I'm not boondocking the electric heater will work until then.
If your's is a 2019 with a Dometic furnace there may end up being an issue with a lot of them though.

You can have the furnace looked at by anyone that is qualified to handle Dometic warranty work. I suggest contacting Dometic to see if they have any mobile repair services in your area as they can frequently get the work done faster than the brick and mortar dealers.

joeclorite · 02-14-2019, 01:55 PM

Quote:

Originally Posted by old_engineer

You can have the furnace looked at by anyone that is qualified to handle Dometic warranty work. I suggest contacting Dometic to see if they have any mobile repair services in your area as they can frequently get the work done faster than the brick and mortar dealers.

Thanks, I will definitely give them a call.

Teamfoxy · 02-15-2019, 05:28 AM

The backlog issue, particularly for warranty work is very common. The good repair shops in our area are usually backloged since there are not that many of them. I think the builders often pay at a lower rate for warranty than most shops charge and are slow to pay, so there is no incentive to move you to the front of the line. I've taken to fixing everything that I can myself and have learned that it just isn't that difficult.

joeclorite · 02-15-2019, 08:22 AM

Quote:

Originally Posted by Teamfoxy

There are two blower cages operating off the same motor. One circulates the air through the heat exchanger to the coach and the other pushes air through the fire box in the furnace itself. Good flow in the coach does not necessarily mean good flow in the fire box. The control board is a possibility, but if the sail switch is faulty or the air circulation is not sufficient, the gas would not flow and the igniter would not try to fire. Hopefully they fix it promptly under warranty.
The good news is that a control board is about $80 on Amazon and a sail and limit switch are under $10 each. They all just plug in, but you still have to disconnect the gas and pull the furnace to get to them.

Thanks Team Foxy,
Do you know where the Air Inlet would be? I see the outlets into the trailer and down to the tanks but for the life of me I cannot see where the furnace is drawing it's air from.

Teamfoxy · 02-15-2019, 09:17 AM

Quote:

Originally Posted by joeclorite

Thanks Team Foxy,
Do you know where the Air Inlet would be? I see the outlets into the trailer and down to the tanks but for the life of me I cannot see where the furnace is drawing it's air from.

This is a typical furnace mounted on an exterior wall. Air for combustion is drawn from the outside into and through the fire box and exhausted back to the outside of the RV. Air from the inside of the RV is drawn into a chaimber that surrounds the fire box and sent back through the heating ducts into the interior. Cumbustible air is never mixed with air from the living space.
I did look at some photos of your model on the Lazy Days website, but they are not good enough to see any outlets.
The service manual for your furnace should give you a better idea of how your model is set up. The owners manual that came with the RV may not. You should be able to download the service manual from Dometic's website.

joeclorite · 02-15-2019, 12:04 PM

Quote:

Originally Posted by Teamfoxy

This is a typical furnace mounted on an exterior wall. Air for combustion is drawn from the outside into and through the fire box and exhausted back to the outside of the RV. Air from the inside of the RV is drawn into a chamber that surrounds the fire box and sent back through the heating ducts into the interior. Combustible air is never mixed with air from the living space.
I did look at some photos of your model on the Lazy Days website, but they are not good enough to see any outlets.
The service manual for your furnace should give you a better idea of how your model is set up. The owners manual that came with the RV may not. You should be able to download the service manual from Dometic's website.

I did find the Installation Manual on Dometic's website and my 18000 btu unit only has an exhaust port to the exterior (which is clean). Both Air Intakes appear to be located internally behind a grill. The unit is mounted vertically in a very tight space and I can't see the actual grills so I'm not sure if there is any debris blocking them. I don't see any exterior debris from the build though.

I have located a very reputable RV Repair Service that is approved by Dometic and they only have a 2 week wait!

So I'll be taking it over to them.

I will post what the resolution finally is to help anyone else with the same problem.

Thanks for your help

e4services · 02-17-2019, 05:55 PM

My guess , no fuel. Look at the troubleshoot steps.
If there is an attempt to ignite, everything is good till them, sail switch etc. THe gas valve is not opening, I think it is three attempts to ignite, Each attempt "click click click" and the control gives up

Jandjstar · 02-17-2019, 06:22 PM

There is a guy in Indian Trail that I totally trust with my 2401 rg. I have used him for over 10 years and very competent. Be glad to give u his number. I bet he can work on yours this week

NeilV · 02-18-2019, 06:31 AM

Its very common for it to take several attempts to get the gas line to the furnace purged and gas flowing all the way to it. Its still possible that the sail switch in the combustion air intake which should be one of the twin ports on the furnaces external faceplate is faulty or that mud daubers or funnel web spiders have made nests deeper into the intake where you can't see them. Sometimes you can clear this with a shop vac on the exhaust or blower on the inlet.

Control boards also do fail and four things have to be detected for the furnace to lite and run.

Combustion Chamber Air Flow
Spark
Gas Flow
Ignition

joeclorite · 02-18-2019, 08:09 PM

Quote:

Originally Posted by Jandjstar

There is a guy in Indian Trail that I totally trust with my 2401 rg. I have used him for over 10 years and very competent. Be glad to give u his number. I bet he can work on yours this week

Thanks, I would love his number.
I am set up with an appt.at Quality RV in Belmont on the 25th. but if it doesn't work out with them I will need a backup.
Thanks for your help.