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Troubleshooting: RV Furnace Lights Then Goes Out

The RV furnace is a pretty important appliance in your RV, especially if you live in a colder climate or just enjoy extra heat in your RV. A furnace light that turns on and goes out can put a damper on your travels.

RV furnace light issues tend to be relatively easy to fix and just require a bit of observation, potentially a clean, or sometimes a new part. 

This article explores why your RV furnace heat light might turn on and off. Problems can include issues with your igniter, pressure switch,  the cleanliness of your furnace, and other problems.

Common reasons why your RV furnace lights and goes out: Flame sensor

When your furnace starts up and produces a propane or natural gas flame, there is a sensor that detects if a flame is present or not and continues furnace operation or shuts down based on what it sees.

The solution? Identify and first attempt to clean the flame sensor in your furnace. The flame sensor has a distinct look and is often a long, potentially curved metal rod that with a plastic bottom. If the rod is tarnished, corroded, or covered in any debris or dust, you’ll want to clean it. 

To clean the flame sensor, you’ll need either steel wool or light grit sandpaper. If your flame sensor doesn’t have obvious deposits, a softer cloth can work too. 

Then put the flame sensor back in and try to turn the furnace on again. According to service technicians, this simple problem is quite common and the furnace will work again.

Your pressure switch could cause your RV furnace to turn off and on

The pressure switch senses air flow within your RV furnace, as air flow is needed to cause the combustion that heats your RV.

The pressure switch itself can fail, causing you to have a furnace that attempts to light, but promptly shuts off.

Thankfully, the pressure switch is relatively easy to replace and often involves just a pair of screws and a couple of wires. 

Note that the pressure switch is usually a circular sensor with a hose in your RV furnace. Amongst mostly squares, this one should be relatively easy to identify.

Your furnace needs a cleaning to stay running

An RV furnace can turn off and on at odd times because it needs to be cleaned. Between the flame sensor and air intake, the furnace might need a solid cleaning in order to avoid overheating.

Furnaces are generally smart and can turn themselves off to avoid causing more internal, or even outside damage, but they can only withstand a certain amount of heat.

The places that most often need cleaning are the front vents on the furnace itself and the intake vents that are outside of your RV. These need to be clear of obstruction to get good airflow and so that your furnace itself can breathe. 

Check around the furnace body too and make sure nothing is plugged by dust, debris, or even animals. Mice and other rodents enjoy furnaces because they are warm!

Unless your furnace is really, really dirty you’ll be able to achieve a clean furnace with little more than some rubber gloves and a can of pressurized air.

Draft inducer motor issues

You might not know that your furnace has a motor that sucks air in from the outside to combust with propane or natural gas. Air doesn’t just linger in on it’s own!

The potential problem? If your draft inducer motor isn’t working right, your furnace could readily turn on and off because it’s not getting any air flow to your furnace.

One way to know about this is whether or not you hear a motor starting near the outside of your furnace. Otherwise, if you have a multimeter, you can test whether or not the draft inducer motor is taking a current.

Gas pressure

Your RV furnace is a bit different from your home furnace, which in most cases runs off an outside line of natural gas. RV furnaces run on your propane or natural gas tanks, which can run out. A blocked line or a simply mostly empty propane tank can cause the furnace to stop and start because it can’t actually heat.

If your liquid propane tanks feel rather light, go and get them refilled and you could easily solve the problem of why it’s lighting and failing.

Blocked lines can also prevent the gas from arriving, so try to blow out your gas lines with compressed air too.

How to tell why your furnace is lighting and failing

Modern high efficiency furnaces have control boards with lights for communication. The control boards light blink either in sequence or a certain number of tires to indicate what the problem could be.

You can consult either the RV furnace manual to learn what sequences mean, or look up the troubleshooting codes on the Internet for your particular furnace model.

RV furnace owners find the blinking lights quite helpful to avoid the need to check every piece of moving equipment in their furnace. The control board can instead relay the problems it has to you.

A non high-efficiency furnace without a control board can be more difficult because they might not have anything in particular to tell you about problems.

Conclusion

An RV furnace can have issues for a large variety of reasons. In the case of many modern high efficiency furnaces, the control board can communicate it’s problems to you. You might have to do a little searching on the Internet to understand what’s saying, but it’s better than digging all the way in and taking things apart.

If you’ve cleaned out your furnace and can’t figure out why it’s not running, consider calling a technician to come to inspect it. They could also teach you about common problems and help you do it yourself next time.

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