Dometic RV Furnace Troubleshooting: (Fixing Heater Problems)

Not all RV vacations are taken in nice, warm locations where it doesn’t get cooler than 72 degrees F. There are many RVers that like cooler weather and enjoy turning their furnace on at night to remain warm. A furnace that doesn’t turn on makes the night longer than it should be.

One of the problems that may arise unexpectedly is a malfunctioning flame sensor. This little part can burn out which allows the safety circuit to shut off the gas valve. This situation may be hard to fix as the furnace is sometimes placed underneath the fridge behind a panel.

To learn more about troubleshooting Dometic RV furnaces, just continue to read our article. it contains the information you want to know about so you can do this task easier and faster. Take a few moments to see how your troubleshooting efforts can be improved.

Common Dometic RV Furnace Problems


One of the common problems you will find with this type of furnace will be the flame sensor. It is designed to send a signal to the main gas valve to keep it open. When it malfunctions or burns out then the signal is lost and the safety system shuts the main gas valve.

This is a low-cost part that you should find at any heating or AC outlet. The only way to fix this problem is to replace the part. However, accessing the furnace is another story and may make the simple task a lot harder to do. If the flame sensor is dirty, just clean it and put it back into position.

Another problem may be that the blower does not shut off and when you go to pull the fuse, you lose the thermostat controlling the AC. Before doing that, you should look for an on and off switch on the furnace. That switch should turn the blower off.

If it doesn’t, you can always remove the red or the black wire and cut the power without affecting your AC controls. Then go to a repairman to have them look at it. If the fan runs but you feel no heat coming from the ducts, then this is an indication that there is a problem with the sail switch

The switch may be defective and will need to be replaced.

How to Troubleshoot a Dometic RV Furnace


This will take two main tools. First, you should open up your owner’s manual to see what it has to say about common problems that arise. The second is you will need a voltmeter. Plus, you need to know how to use one in order to find the problems that need fixing or eliminating those that don’t.

Your solution will depend on the problem that has caused your furnace to stop working. In most cases, if cleaning doesn’t work, you may need to repair or replace the part, with the latter being chosen the most often.

Also, your owner’s manual should have a page on different error codes. Some furnaces will flash between 1 and 5 times telling you what is the problem. You have to figure out what code is flashing to find the problem.

Then, some problems may have multiple sources. For example, if the furnace fan does not come on but the thermostat is on, then you are either getting no power from the battery, there is a bad time delay relay, or bad wires.

This link should help you.

Dometic df Series Furnace Troubleshooting

There is a page in the owner manual that lists some common and simple problems that can arise while you are away on your vacation. And most have multiple sources for their cause.

For example, if the furnace does not light and the blower does not turn on then you could have a blown fuse, the breaker got tripped, the power is too low, the intake or exhaust vents may be blocked or the furnace got locked out and needs to be reset.

If the furnace does not light but the blower does turn on, then there may be air in the LP line which needs to be purged. Or the thermostat is not set high enough or not turned to the Heat function

Then if the furnace shuts off too early and long before the set temperature level, check the vents to make sure they are open and not covered by anything. Or check the air intake to make sure it is not blocked

How to Turn On a Dometic Furnace


If your Dometic furnace is a DSI style heater, then never try to light the burner by hand. It has an automatic system that will light the gas for you. Then before you turn the system on, sniff around the furnace to see if you can smell any gas. If you do, then there is a leak, and do not turn the furnace on.

If the air is clear, you need to turn the gas valve on. This is to be done by hand only and never use tools. Do not force the valve if you cannot turn it to the on position. Call a qualified repairman to look at the problem.

Once all this is done, make sure the power switch is turned to the on position. If it isn’t, the furnace will not light. This switch can be found inside the door on the door models and the outside of the furnace in non-door models.

Then set the thermostat temperature to the desired level and your furnace should light.

Dometic Furnace Won't Ignite

We have mentioned the flame sensor earlier. If it is malfunctioning, your furnace will not ignite or stay lit for very long if it does. That part needs to be replaced if it has gone bad or has burned out.

Another problem that will stop the furnace from igniting is that the furnace has been locked out for some reason. To reset it, you need to turn the thermostat completely off and then back on right away to reset it.

Or, the sail switch got dirty and malfunctions. this is a simple fix that takes a little cleaning before putting it back and trying again. Another source to try is to check your LPG supply. If the furnace does not light your tanks may be low or on empty.

Turn on your stove to see if it is getting any propane. If not, your tanks are probably needing to be refilled. If it does turn on and keeps a steady flame, then your gas lines to the furnace may be blocked.

Finally, get your multi or voltmeter out, and you do not need an expensive one, and check to see if the electricity is flowing as it should.

Why Does My Dometic Heater Keep Shutting Off?


Like other common problems, there are multiple sources for this issue. One is that you may have an electrical problem. This problem is caused by too little input voltage or there is a short in the system somewhere.

There could also be a bad connection with the shore power outlet. Or it could be as simple as the propane tank being too full and it was not properly bled to allow a smooth flow of gas to reach your appliances including your furnace.

Another issue may that may cause this problem is moisture in your propane tank. This moisture will help freeze the pressure regulator and cut the propane supply or lower that supply down so far it won’t let the furnace keep burning.

The solution to this last problem would be to find a good LPG outlet and have them inject some methanol into the tank. Or insulate the regulator to keep it from freezing and add a trouble light to heat the regulator so it won’t freeze overnight.

But to check that issue, you should light up your stove and other gas-powered appliances to see if they are working. if they are, then the regulator is not freezing overnight.

Finally, if the blower fan is dirty it may not blow enough air to trip the sail switch. Clean the fan.

How do I Reset My Dometic Furnace?

Generally, this is a very simple process. All you have to do is turn the power off for a couple of minutes so the thermostat has time to reset itself. Then you just turn it back on and your furnace lockout should be reset and everything should be working like normal.

If you are still having problems after trying this solution, then you may still have some air in your propane lines that need to be purged. Since you can’t light the furnace, light the water heater instead.

Let the water heater run for about 30 minutes and your furnace should relight on the first try. The operative word is ‘should’. Or you could light the stove burners and do the same thing. Just do one first, till it burns steady, and when it does light the other burners and repeat.

After that, you should light the fridge to make sure its gas flows smoothly. The fridge should be the last appliance you turn on. You want to purge the air from all the gas lines to make sure the gas flows properly and without hassles.

How Long is the Dometic Warranty?


If you buy a new Dometic furnace, you can return it within 30 days provided it hasn't been altered, used, and still sits in the original packaging. The heat pumps seem to have a 2-year warranty.

If you have any questions about their policy on heat pumps or have lost your warranty information, just click this link and you will be taken to that page. The regular furnace warranty is also for two years and it has 12 points you should look over carefully.

To read their warranty or copy it, just click on this link. Then if you have other Dometic products, they have a specific warranty page with links to specific products and their coverage. Just click here to find that list.

Most Dometic products seem to be covered by the same 2-year term and strict guidelines. It would be best if you read the warranty details before you buy their products.

How do I Contact Dometic?

This will be easier than trying to access their products once they are installed in your RV. They have an English website that provides you with all the information you need. here is their landing page link.

From there, you scroll down to the bottom of the page and look for the words, contact us. That link will take you to their contact page at this link. On that page, you will find the e-mail address of every department you may need.

If that e-mail is too slow, then there is a link to click that takes you to the support form. Fill out that form and submit it. Or you can use their find a dealer web page to find one close to your home and talk to them in person.

That may be your best option if you are not getting any results from using the form or their e-mail addresses.

Some Final Words

There will be times when you will have problems with your Dometic furnace. The best solution if the above information doesn't work for you is to talk to a qualified repairman.

You can try your local handyman but it is always best, even if it is expensive, to talk to those who know the product best. Or use the above solutions to do it yourself after the warranty has expired. The hardest problem you will have is accessing the furnace to fix it.

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