7 Reasons Why Your RV Furnace Won’t Ignite?

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Last Updated on April 10, 2021 by Tanmay Sarkar

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An RV furnace is a very useful appliance, especially during cold chilling nights. Most of the RV furnaces still rely on liquid propane as a fuel source but need electricity to run few components.

An RV furnace failure is like a nightmare if you do not have other things to warm yourself.

In this article, we have brought to you troubleshooting tips that you can try to resolve minor issues related to the RV furnaces. Major issues such as a damaged component of the furnace may not help you out.

Troubleshooting An RV Furnace That Won’t Ignite

An RV furnace may not work due to reasons that are indicated below, please used the following steps to troubleshoot the problem.

1. Propane Tank Gas Lines

Diagnosing The Problem: before diagnosing the tank gas lines we should always check whether there is gas in the tank or not. To check this you can use any other appliance that uses propane such as a two-way refrigerator or by turning on the internal propane range.

If the appliances are working fine then it’s sure that there is no problem with the supply of propane.

Addressing The Problem: if there is a gas leak inside then you may smell it easily. If not, then look for the lines that are outside the RV. Here it will not be easy to smell the gas because of the air ventilation.

If possible then you can try to use shampoo or any other liquid soap. Mix shampoo with water in a bowl and use a sponge and apply it on the gas lines. If there is any leak then you will come to know where the bubbles are forming.

Or you can use a bare hand to detect the leak but this will be difficult.

Sometimes the propane coupler comes loose in cold weather. Take a moment to check them to make sure everything is in its position.

Another possibility of a gas leak is where the propane lines enter the RV. The gasket can wear on the hose to cause a leak.

If you find a gas leak then use duct tape to fix it temporarily. But do not rely on this as propane leak is dangerous for you and the camper.

Video: RV LPG: Finding and Repairing System Leaks

2. Electrical Problems

Generally, RV furnace igniters run on 10.5 volts, if one or two onboard batteries are low or dead then there would be not sufficient electric spark to ignite the system.

Sometimes the circuit breaker in the furnace can trip down which causes igniter failure. Please check the panel to make sure the furnace and thermostat are in the “On” position.

Common Problems That Cause Igniter Failure

Look at the common problems that causes igniter to fail.

1. Old Igniter

Electric ignition system works for a long time before they become useless. Look if the igniter is not very old to work.

2. A Faulty Temperature Limiting Switch

The temperature limiting switch is a safety feature that turns off the burner when the furnace becomes too hot. So, see if the air filters are clear and not clogged which may cause the problem or the switch itself may cause the igniter to turn off early.

3. Wrong Type Of Igniter

A wrong igniter will not work in your furnace as it won’t match the furnace voltage. Sometimes the problem is not as severe as we think.

4. Overpowered Current

A power surge may burn out the igniter itself, generally hot surface igniters fails more often due to power surge.

3. Electrical Wiring Problem

If you find your onboard batteries delivering sufficient power then move on to the next step, that is to find a loose wire or a damaged one.

Finding a problem in the wire is not an easy task. You have to start with the furnace itself if there is power in your RV. Check all the connections on the furnace and make sure all wires are in their position.

Check other appliances which are running on electricity.

If other devices are running well then look for the line that powers the furnace. Sometimes a wire can get damaged inside without any signs of damage on the protective coating of the wire.

In this situation, a professional will the best troubleshooter.

4. Low Or Dead Battery

If the onboard batteries are low or dead then they will not deliver power to the thermostat or the furnace. It won’t be able to ignite and sometimes the fan will not work at all.

You can use a multimeter to check the supplied voltage, anything less than 10 volts will not work. A backup battery can be useful in this situation.

5. Battery Corrosion

The corroded battery can be one of the problems especially if the battery is old. Look at the battery terminal and the connectors for possible corrosion.

Generally, a corroded battery will show signs of corrosion that is the greenish, white, or gray-colored material buildup on the terminal.

Clean the battery terminals if you find any corrosion on them. If done in the right way it will begin delivering power to the furnace again.

How to remove battery corrosion

Try the steps below to remove or clean the battery terminals:

  1. First, disconnect the battery cables
  2. Check the battery cables for a possible damage
  3. To remove battery corrosion use a battery cleaning agent
  4. You can also use soda to clean the terminals
  5. Scrub the terminals with a brush to remove corrosion
  6. Once all the corrosion is removed, rinse the battery and the cables and let them dry completely.
  7. Apply anti-corrosion washers once things dry, they are also known as battery terminal protectors.
  8. Once done reconnect the battery to the vehicle.

6. Thermostat Problem

A thermostat is a device that cuts the power supply to the furnace when there is sufficient heating. Most of the time it lasts longer than the furnace itself but still, it can fail.

The sensor inside the thermostat can burn which can lead to the total failure of the thermostat.

You will need to replace the thermostat in this situation. Sometimes loose wire or a dead battery can cause the thermostat to fail.

If you find any loose wire then carefully fix it to start the furnace again.

In some cases the thermostat isn’t connected with the onboard 12 volt batteries, in this case, they run on AA or AAA batteries.

You may see the display screen blinking or is not responding to the press of the button. Sometimes a blank screen is what you see.

In this scenario, you have to replace the batteries of the thermostat and also look for any corrosion which is disturbing the power supply.

7. Fuse In The Furnace Is Blown

A fuse is used between the DC supply and the RV furnace which can blow due to a short circuit or power surge. A black-colored fuse means it has to be changed.

What To Do If Furnace Blower Comes On But Won’t Ignite?

Many times the RV furnace may ignite but the blower won’t deliver hot air or the stream of air may be weak. This might be due to any one of the reasons below:

1. Pilot light issue

A pilot light is a small gas flame usually natural gas or liquefied petroleum gas which serves as an ignition source for a propane-powered furnace or gas burner.

A pilot light problem generally arises due to failed safety sensor or airflow issues. This can cause the furnace blower to come but not to ignite.

To troubleshoot the problem, start with the sail switch. A sail switch is also known as Van Switch or Flow Switch which is a mechanical on/off switch that controls the airflow in the furnace.

If there is less airflow then it stops the furnace from igniting but the blower will start. The failure of the sail switch is also due to insufficient return airflow or less ventilation.

2. Blower fan issue

A blower fan may get damaged completely or start falling slowly. So, if there is little heat then the fan motor is slowly getting damaged.

The issue can be with any component of the fan such as bush, bearing, or wiring. Troubleshooting them one by one may resolve the issue. Fan with worn-out bush and bearing produces a lot of heat which can be the sign to fix it or replace it.

Sometimes the issue is the loose wire. Generally, fan connections are soldered well but due to aging, they may get loose. If you find any you may solder it back to fix the problem.

3. Thermocouple issue

A Thermocouple is an electrical device that consists of electrical conductors forming an electrical junction. It produces a temperature-dependent voltage as a result of the Seebeck effect. It is a sensor that is used to measure the temperature at the furnace. 

It is used in the furnace to ensure that there is a pilot flame before it opens the main gas valve.

So, if the thermocouple is burned out or it fails the furnace won’t work and the pilot light goes off.

Knowing about the kind of ignition that the furnace is using will help you to diagnose the problem and even if you fail you can better communicate with the professional.

The two main types of electric ignitions are

1. Intermittent Pilot

In intermittent ignition design, a small spark is used to ignite the pilot and the burner. Whereas in standing pilot design the pilot light is constantly burning but in intermittent design, it lights only during the heating cycle.

2. Hot Surface Ignition

In a hot surface ignition system electricity is used to heat the metal and ignite the gas burner.

Signs Of A Furnace Problem

Look at these signs to know there is a problem in the furnace.

1. Limited Heat

The amount of heat from a faulty furnace won’t be much as it was earlier.

2. Frequent Cycling Of Thermostat

A faulty burner will cause the thermostat to constantly start and stop the furnace. This causes an interruption in heating cycles.

3. Overactive Blower

If the limiting switch is inaccurate then it will turn off the igniter. This causes the blower to run to clear the warm air from the surrounding.

If you find these problems in your RV furnace then call a professional. Up-to-date maintenance will cause fewer problems in the furnace.

How to test RV furnace ignitor

Frequently Asked Questions

Q1. Can hear your furnace click on but it does not fire up? /  RV furnace clicking but not lighting

A1. When the furnace makes a clicking sound but does not provide heat then it is due to the spark igniter. The spark igniter try’s to ignite the pilot light but fails to do so. There is an issue with the ignition system of the furnace which needs to be fixed.

Q2. Can I manually light my RV furnace?

A2. Try the following steps to manually light the RV furnace. Remember, to consult the owner’s manual before performing the following steps as additional steps may be required.

  1. Turn on the tank: turn off the electric power supply to the furnace. Now, turn on the propane tank and also turn the fan to auto. After this turn the thermostat to the highest heat setting and let the fan run for few minutes.
  2. Press pilot know: first, remove the furnace panel and turn the gas dial to the pilot position and hold the knob.
  3. Light the pilot: if your furnace has a striker ignition system then press it several times. You can also light the pilot with a lighter or match. Now release the knob and turn it to the “on” position.

Note: If the pilot light is not ignited then try again and this time, try to hold the knob for a longer time. If it starts then you can now set the thermostat to the desired temperature.

Q3. Does my RV furnace have a pilot light?

A3. Newer RV furnace models had replaced the pilot light with the direct ignition system. You have to open the furnace panel to check if there is any pilot light in your RV furnace.

Q4. Do RV furnaces run on electricity?

A4. All most all RV furnaces use liquid propane to heat the RV. But still, RV furnaces may use electricity to ignite or control the thermostat. Heating is done with propane but other important components such as thermostats need electricity to run themself.

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