RV Furnace Troubleshooting Basics

A large motorhome driving along a rural highway.
  • .25-8
  • Intermediate
  • 5-1,000

Having a furnace in an RV can be a very beneficial feature, especially if you plan to travel to colder climates or during colder times of the year. Just like in your home, this added fixture will keep the place plenty warm for a comfortable sleeping atmosphere. However, these can still encounter mechanical issues even when seldom used. RV furnace repair isn't always difficult, and you don't necessarily need a pro to fix every problem. Listed below are some troubleshooting basics that can be helpful to you.

Pilot Light Is Out

blue pilot light flame

Sometimes you may notice that the pilot light isn't lit. First, check the obvious problems off the list by checking the propane tank. Make sure it is turned on and not empty. If this doesn't solve the issue, you should also take this time to check the propane regulator. Turn on the stove burner and observe the color of the flame. Ideally, you should see a blue flame with only a hint of yellow at most. If the flame color remains consistent, this means your propane regulator is working just fine; if not, it will need to be replaced. This problem can also affect your hot water heater.

A misaligned thermocouple can also stop the pilot light from staying lit. It should be positioned properly in the pilot flame, so make any necessary adjustments if it isn't sitting right, or replace it at this time if it's broken altogether.

Also be sure to check the furnace vent for blockages. A pilot light needs oxygen to burn and without venting, it can't get any. Any obstructions will likely be near the vent opening.

Fan Does not Run but Furnace Still Produces Heat

If you notice that your machine is still giving off heat yet the fan is not running, there are several sources you can check. Heat means that there is gas flowing so you can avoid checking the propane again.

The thermostat itself can be the culprit of a dead fan even if there is heat. Glance over the settings first to be sure they're correct. Then, if that checks out, remove the cover and inspect the anticipator adjustment. This will have a sliding contact over either a bare wire or a bare wire wrapped around an insulating material if your specific thermostat has one. Adjust the slider in either direction slowly. Wait for at least 30 seconds in each position and listen for the fan to start. If this does kick the fan on, then find a place close to the original position that will work and replace the cover. If not, you likely will need to replace the thermostat altogether.

You can also examine the wiring to the fan itself for shorts or fraying. For heat to be generated, electricity must be flowing through your unit, so before you take a closer look, be sure you disconnect the furnace from its power source entirely. Find the fan in your specific unit and trace the wiring from it until you've checked it completely or until you've found the problem. It can be tricky to open up the furnace enough to get to this wiring, and it can be a nightmare trying to completely replace a wire, so if you're not confident in this task, get professional help.

Fan Does Not Work and Unit Produces No Heat

In this case, you need to first make sure that the battery isn't dead and that you have twelve volts to the furnace. Even if these check out, electricity to the machine may still be the problem; inspect your breaker box to be sure you haven't tripped a breaker or blown a fuse.

Your thermostat's anticipator regulators can also be the source of this problem as well. Check for the anticipator's slide position again and replace the thermostat altogether if needed.

Fan Is Running but Furnace Produces no Heat

travel trailer parked in the  snow

An RV furnace has an internal sail switch that will prevent the machine from igniting in cases of air flow being insufficient for combustion. As a result, the vent will work, but no heat will be produced. Several things can be checked for a cause in this case.

A bad battery can once again be at fault here, as can a bad electrical connection to the blower's motor. Without sufficient electricity, the blower cannot produce the force it needs to trip the sail switch. Check the battery for correct voltage, and follow the wired connections from the blower if you suspect damage.

Insufficient air flow can also be triggered by poor ventilation. It is essential to check if the heat registers are closed or obstructed and to clean them out completely if they are. Some furnaces can experience problems even with a small blockage, so be thorough.

Since RV furnaces can vary widely by model, and based on whether they are direct discharge or ducted types, some of these methods may not apply to your situation. However, these general tips should provide some answers for the average DIYer stumped on the cause of their issue, as well as a little advice on what to do about it.