RV Furnace How-to and Troubleshooting Guide

Keeping your RV warm is a priority if you plan to spend winter in it – or at least part of the cold nights. While insulation will play a critical role in keeping the cold out, you will need some active heating to keep you cozy on the coldest nights.

A furnace is a great way to keep any room warm. Getting a compact RV furnace could be a good solution if you don’t want to tinker with AC units with heat function or a diesel heater.

Here is a look at the problems you might encounter when living with an RV furnace and how to solve them.

Why is my RV furnace not kicking on?

Here are a few reasons that the furnace is not kicking on;

Thermostat

The thermostat can be an issue if your furnace is not kicking on. You should first ensure that the thermostat is switched to the heating function. Next, ensure that the temperature you have the thermostat set on is lower than the temperature in the home.

You may also have an internal problem with your thermostat, which needs to be repaired by a professional.

Power Issues

Regardless of the type of fuel that you use to power your furnace, it needs electricity. So, you should ensure that the fuse that powers your furnace has not tripped. Next, ensure that the power cord has not been damaged and that the power switch is in the “on” position.

Finally, if you notice any burn marks on the control board of the heating system, there may have been an electrical short. You would need to contact a professional to repair the problem.

The Blower Component

If there is a problem with the furnace’s blower component, your furnace will not kick on. Most models have an inspection window. If you look through the window and the light is green, your blower is functioning properly. However, if the light is not lit up or red, there is a problem which you should contact a professional to repair.

Full Condensate Pan

The heating system will not kick on if the reservoir in the condensate pan is full. You should contact a professional to come to look at your unit. They would need to check for pipe blockages. If the pump has lost all power, it may need to be replaced.

Pilot Light

If the pilot light on your furnace is out, the furnace will not turn on. You can try lighting the pilot. If it stays lit, your furnace will kick on. If it does not, there could be a problem with the assembly or the sensor, and a professional would need to come in and fix it.

Check this too: Electric RV Water Heater How to & Troubleshooting Guide

Having your furnace stop working can be very stressful, especially when it is cold outside. However, knowing what could be causing the problem and when to call a professional can make your home warm in no time.

Do RV furnaces have a reset button?

Yes. All furnaces are equipped with a reset button. They are generally red or yellow and are located inside the blower compartment.

How do I reset my RV furnace?

First, turn off the power supply to the furnace by turning off the breaker in the circuit box. Next, locate the reset button on the furnace and press it to reset the furnace. It is usually located inside the blower compartment on the side of the blower motor. 

Note: Be cautious as the housing may be hot.

Why is my RV furnace running but not producing heat?

Below are some reasons why your furnace is not producing heat

Fuel Issues

The only reason behind a furnace not supplying heat is your fuel source. The most obvious issue, and the first one to check, is your propane supply. Make sure you have adequate propane to run your RV’s furnace.

If you don’t have a gauge handy, you can check your tank level without a gauge.

You’ll also want to ensure your propane tank valve is open and your onboard propane regulator hasn’t failed or is clogged. 

Sail Switch Failure

Another common reason for an RV furnace that’s running but isn’t producing heat is the failure of the sail switch to open. The sail switch is one of two safety switches in your RV furnace; if it doesn’t open, your RV furnace won’t produce heat.

The sail switch can fail over time or be clogged with debris such as dust, pet hair, insect nests, or rust. In some cases, the sail switch may be able to be blown clean and continue to work properly. However, in others, it will need to be replaced.

Bad Gas Valve

If your RV’s furnace fan runs but the furnace isn’t producing heat, you may also have a bad gas valve.

Take a seat near the exhaust port of your RV’s furnace while someone else works the thermostat to trigger the furnace to come on. First, you should hear the fan turn on when you fire up your RV furnace. Then the solenoid should make a clicking sound. Next, you should hear a rapid ticking sound (the ignitor) and smell propane gas.

However, if your RV furnace’s fan turns on and you hear the click of the solenoids and then the rapid ticking sound, but you do not smell propane, you’ve likely got an issue with your furnace’s gas valve.

Failure of the Ignitor

Next in line in the furnace lighting process is the ignitor, so let’s troubleshoot that element.

Once again, seated at the exhaust port of your RV’s furnace, listen carefully to what happens when the thermostat is turned up inside your RV.

You should hear the fan turn on, followed by the click of the solenoid. Next, you will either hear the rapid ticking or no ticking. If you DO smell LP gas at this stage, but your RV furnace doesn’t ignite, the problem may be the ignitor.

Faulty Control Board

And finally, if your RV furnace runs without heat, there could be an issue with the control board. This is essentially the brain of the RV furnace. Power needs to get TO the control board and travel through the control board to the other furnace components.

RV Furnace Ignites and Produces Heat but Shuts Off Prematurely

Here are some reasons why your furnace keeps shutting off;

High-Level Switch

The high-level switch is the second of two safety switches in your RV’s propane furnace. It’s the job of the high-level/high-limit switch to shut down the furnace if the temperature in the combustion chamber reaches a certain temperature. 

This excess heat can be caused by a leak in one of the combustion chamber tubes or by the improper exhausting of the hot air (which could be due to low voltage causing the exhaust fan to run too slowly or by some other failure in the exhaust system).

To address this, ensure that the exhaust is not blocked by dust, dirt, debris, insect nests, etc., and that there is proper airflow. Also, check for anything blocking/slowing the air intake for the furnace inside your RV.

You can also check the tubes in the combustion chamber for damage such as holes or cracks.

Your high-level switch may be bad if you do not find issues after doing this. You can test your high-level switch with a multimeter.

NOTE: confirm that the part is correct for your make/model before ordering.

Flame Sensor

The flame sensor is a critical safety component of your RV propane furnace. When the propane gas is ignited, the heat causes the flame sensor to produce a current of electricity.

However, if the flame in the combustion chamber of your RV’s propane furnace goes out, it will shut down the furnace completely. This occurs so that gas doesn’t continue flowing if it isn’t being combusted.

So, if your furnace ignites and begins to produce heat but then shuts off, the issue could be the flame sensor. The flame sensor is generally part of the ignitor assembly.

I can hear the RV furnace click on, but it does not fire up

If you turn up your RV’s thermostat and nothing happens, your fan/blower motor isn’t starting. A non-functioning fan/blower motor could have several causes.

Inadequate Power Supply

A traditional RV propane furnace requires a strong 12V power supply for various furnace components to operate. So if your furnace doesn’t kick on at all, this could be due to low battery voltage.

You’ll first want to check your 12V power supply to ensure you have adequate 12V power to run the furnace. If you have a dead house battery, for example, the furnace won’t be able to function.

Confirm that you have a strong 12V power supply coming from your RV’s batteries, and then check the connections along the wire running from the thermostat to the furnace’s circuit board.

Relay for the Blower Motor is Bad

Another reason your furnace fan may not be kicking on involves the relay on the circuit board. The blower/fan can’t start if the relay isn’t opening. In this case, you can troubleshoot by testing the relay.

To do this, you’ll bypass the relay to see if the fan will run on the direct power from the battery. If the fan functions using direct power, then you know that the fan is good, and the problem is likely to be the relay.

However, if the fan doesn’t run on battery power, your relay is likely okay, but the fan itself is problematic. It could be seized from rust if it’s been a while since you last used your furnace.

Note: The blower motor must be replaced if you’re hearing a squealing sound from your RV furnace.

Is there a fuse for the RV furnace?

Yes. The RV furnaces need a fuse for the ignition system. If a fuse is missing in an electrical unit, it can cause damage to components in the wiring and even trigger a fire.

RV furnace won’t ignite

Below are a few reasons why your furnace won’t ignite. Some are simple fixes, and others may require help from a professional.

1) Problems with the Propane Tank

Propane tanks are a common fuel source for RV furnaces. You can easily swap the empty tanks out for full ones at most gas stations on the road. A common problem with the tanks is a closed valve preventing gas from flowing through the line to the furnace.

Older tanks and ones with low fuel levels can also freeze in cold temperatures. Recycled propane tanks can also fail to deliver gas to the furnace. Often the problem is due to a clogged valve. Manufacturers sometimes repaint recycled tanks, and the paint can temporarily block the main tank valve.

2) Problems with the Propane Line

When the propane tank’s main valve is open, there isn’t a problem with the regulator. Instead, the small device near the tank controls fuel flow. The next step is to check the line. Chances are air has gotten into the line. It can create a blockage preventing fuel from reaching the furnace.

The coupler can also loosen in cold weather allowing the gas to escape. Gaskets can also wear out, resulting in leaks. Either of these issues will prevent the RV furnace from igniting.

3) A Burned-Out Thermocouple and Pilot Light

The thermocouple is a small tube in the center of the pilot light and provides the electricity needed to keep the gas valve open. The small part does wear out over time, though the brass tubes are designed to last for years. Unfortunately, when the tube is worn out or broken, it can’t detect the flame from the pilot light keeping the gas line valve closed.

Soot and dirt can also block the pilot light preventing the flame from being detected by the thermocouple. It can also cause the flame to go out continuously. The low flame or lack of a consistent one isn’t enough to engage the thermocouple.

4) Problems with the Thermostat

The furnace doesn’t know when to turn on and off without a thermostat. It is the “brains” behind the RV’s heating system. The component and the small parts break down, but it usually takes several years. Thermostats are designed to withstand a lot of use.

Some are battery-powered. Always check the batteries if this applies to yours. Loose wires are another reason your thermostat could be giving you problems. You could also have corrosion around the connecting wires. Any of these issues will cause problems with your thermostat.

5) Problems with Airflow

There are two main reasons your heater is running, but you’re not feeling the warm air. It is usually either the fan’s motor or loose wiring. Older fans can have worn-out bushings or bearings. The fan’s motor may be warm but not push out the hot air. Also, check the fan blades. Dirt and debris can collect inside to prevent the blades from rotating.

Loose or broken wires will also cause problems with airflow. A loose wire will slow the fan down or cause it to run intermittently. Broken wires will stop the fan blades, so only a small amount of heat is released into the RV.

6) Simple Electrical Issues

Along with wiring problems, electrical problems with your furnace are also caused by tripped circuit breakers and low onboard batteries. A low or depleted battery won’t have the power to ignite the heating system or control the thermostat. Likewise, a tripped circuit breaker will prevent the electrical spark needed to light the pilot light.

RV propane furnace not working

Below are some reasons why your furnace is not working

The Outside Exhaust Vent is Blocked or Dirty

The furnace’s exhaust port must be free of debris to ignite and operate normally. Unfortunately, mud daubers, spiders, or other insects sometimes make their way inside from the exterior exhaust port and build nests that create a host of furnace issues.

Removing the exhaust housing, checking for nests and other debris, and cleaning the area completely may help. Installing screens can be extremely helpful in preventing this from happening in the first place.

You can also purchase a kit with various screens for this and other exhaust ports on your RV.

The Air Return Grill is Blocked or Dirty

RV furnaces often experience long periods of no use; some are used only occasionally, if ever. Always inspect your RV’s air return grill for dust, pet hair, dirt, and obstructions before using the furnace. Be sure nothing is blocking the fresh air return while using the furnace. Keep items away from the return grill while the furnace is in use.

Incomplete Combustion

Check the exhaust vent for soot if your RV’s furnace isn’t working properly. The presence of soot indicates incomplete combustion. When the exhaust vents aren’t hot, use a finger to check for soot at the exhaust ports. 

Make sure to check the exhaust vent only when the vent isn’t hot. Then, check for black soot in and around the exhaust vent using a finger.

Should you find black soot in this area, don’t operate the furnace because incomplete combustion can expose you to dangerous carbon monoxide gas. Instead, have your RV furnace inspected by a qualified technician ASAP.

RV furnace thermocouple failure signs

Start by doing a visual inspection. Look out for;

• Signs of contamination on the tube can include discoloration, cracks, or pinholes.
• Then check the wiring for any signs of wear or corrosion like missing insulation or bare wire.
• Finally, visually inspect the connectors for physical damage because a faulty connector can affect the reliability of the test reading.

If you cannot see or detect problems, proceed with the test.

How to perform an open circuit test of the thermocouple

• Before the test, turn off the gas supply because you must first remove the thermocouple.
• Remove the thermocouple by unscrewing the copper lead and connection nut (first) and then the bracket nuts.
• Next, take your meter and set it to ohms. Next, take the two leads from the meter and touch them—the meter should read zero. Once this check is done, turn the meter back to volts.
• For the actual test, turn on your flame source, and place the tip of the thermocouple into the flame, leaving it there until it is quite hot.
• Next, attach the leads from the multimeter to the thermocouple: put one on the side of the thermocouple, and attach the other lead at the end of the thermocouple in the pilot light.
• A working thermocouple will give a reading of between 25 and 30 millimeters. If the reading is less than 25 millimeters, it should be replaced.

Note: If you are inexperienced, we’d recommend calling a licensed heating contractor to perform the test.

Does an RV furnace need electricity?

Most RV furnaces use electricity to ignite or control the thermostat. Onboard RV furnaces do not run solely on electricity. However, the furnace built into your RV’s HVAC system does. Fortunately, there are a variety of electric heaters on the market you can add to your RV’s interior for extra heating.

That said, most onboard RV furnaces are primarily run-on liquid propane, a pretty efficient fuel source. You can also convert your furnace to run on electricity to reduce costs or emissions or avoid having to travel with LP gas.

Will the RV furnace run on battery?

Yes. RV Furnaces are powered by propane and electricity. Most RV furnaces operate on 12 volts DC power and can run from a battery, generator, or 110 using your RV’s converter when it is plugged into electricity.

How to use an RV furnace for the first time – must do preparations

Before operating the furnace, check around the Furnace area and floor for the gas smell and check the fitting with a leak test solution. Do NOT proceed if a gas odor exists around the furnace or floor area. 

Follow the instructions below;

• • Turn the gas control valve by hand only. Never use tools. If the valve does not turn by hand, do NOT attempt to repair it. Instead, call a qualified service technician.
  • Read the following BEFORE proceeding:
    • During the initial firing of the furnace, a burn-off of excess paint and oils remaining from the manufacturing process may cause “smoking” for 5 – 10 minutes.
    • The Furnace is equipped with a power switch. Therefore, gas will not flow to the burner, and the furnace will not operate with the switch in the OFF position.
    • Door models have a power switch located inside of the door.
    • Non-door models (LD or Small Vent) have a power switch outside the furnace.
• Turn the thermostat to the lowest setting.
• Turn OFF all power to the furnace at the main power supply.
• At the exterior access panel, turn the switch on the furnace to the OFF position.
• Wait five minutes, then check for a gas odor.
• If a gas odor exists around the Furnace or floor area, follow the instructions in the warning box on the cover page.
• If no gas odor is present, proceed to the next step.
• At the exterior access panel, turn the switch on the furnace to the ON position.
• Turn ON the main power supply.
• Set the thermostat to the desired temperature.

How to clean and maintain your RV furnace

Routine cleaning for an RV furnace may require the removal of the heating unit. Once removed, you can proceed to the next step:

• Wipe away loose dust and dirt.
• Vacuum the different parts in and around the furnace, including the ducts and exhaust tubes.
• Clean the heating unit’s metal components.

Note: the exact process of cleaning an RV’s furnace might be different for each vehicle. It’s because the placements of the heating units are often different for every RV. So keep reading to know where to find the furnace in your RV and how to remove it if necessary.

Where Is My RV Furnace Located?

The location of your RV’s furnace often depends on the vehicle’s make and specific model. Here are some examples of certain RVs and the site of their furnaces:

• 2017 Coachmen Freedom Express Ultra Lite: The furnace is underneath the kitchen cabinet area, encased in a dark brown cover.
• 2021 Entegra Odyssey 26D: Find the furnace behind a gated cover underneath the oven.
• 1999 Winnebago Adventurer: The location of the furnace is on the opposite side of the coach. Also, sealant and screws might need removing for these objects can get in the way of accessing the RV heating system.
• 2018 Jayco Eagle: The RV manufacturer mounted the furnace. But it’s hidden in a plywood box under the couch.

Note: Check the vehicle owner’s manual if you’re unsure about your RV’s furnace location. Consult the automobile maker if the guide doesn’t specify the location of the heating unit.

How To Remove an RV Furnace

Before proceeding with this project, note that the specific steps to take apart a furnace from an RV often depend on the brand and model of the vehicle. For example, some furnaces might be behind sealed coverings.

Remove Sealant & Fasteners

Moreover, different securing materials, such as screws and sealants, may secure those encasements’ furnaces. Therefore, the removal of these accessories might come first.

Set up A Flat Workspace

Also, you need a flat surface like a sturdy table to place your furnace upon its removal. Don’t put the furnace on rough terrain since doing so can damage some parts.

Check this too: How to Heat an RV Without Propane

Turn OFF The Fuel Line

The final step of the preparation process, perhaps the most important, is to turn off the gas line attached to the furnace. Leaving the gas turned on while trying to remove the heating system can invite health hazards.

Once you complete the preparations, here’s a guide to let you check what removing a furnace from a Forest River Prime Time Lacrosse 337RKT RV looks like:

Items needed

• Phillips screwdriver 
• Paint scraper

Removal Steps

• Remove the furnace covering. Consult RV’s owner’s manual to know what type of casing you’re currently dealing with.
• Unscrew the exhaust vent with the Phillips screwdriver. Next, remove the exhaust vent and the rest of the screws holding the container.
• Next, remove the screws that connect the furnace to its container’s outer ring.
• If the RV manufacturer sealed the encasement with silicone, use a paint scraper to remove the sealant carefully. Remove the ring afterward.
• Loosen the gas line and push it into the hole at the top of the heater.
• Take away the furnace’s strap before pulling it out.
• Pull the furnace’s container a few inches out. Then, return to the inside of the RV and disconnect the ductwork and electrical from the heating unit.
• Move back outside and remove the furnace and its container out of the RV. Place the heating system on the table to proceed with other projects, such as cleaning it.

How Do You Clean Your RV Furnace?

Some RV models require you to remove the furnace to clean it properly. But note that you shouldn’t attempt to remove a sealed furnace, particularly one with a gasket seal. Attempting to apply an unnecessary force to the gasket may result in a carbon monoxide leak.

Immediately refer to the RV manufacturer or the vehicle’s manual to learn how to deal with this concern. But if you can remove the RV furnace safely, you should know that regular cleaning for the vehicle’s heating system usually doesn’t need special equipment.

Here’s how to do this cleaning job:

Use a clean microfiber cloth to remove loose dust and dirt in and around the furnace.

Vacuum the heating unit to suck up more filth and gunk you couldn’t pick up using the cloth. Don’t forget to use the vacuum cleaner on the exhaust and ductwork.

Finally, use a damp cloth or rag to wipe the metal components.

While cleaning the RV furnace, you may also want to continue the routine maintenance to check the heating system for potential problems. Some of the areas you may inspect are:

• Fuel supply
• Intake or exhaust tube
• Battery