If you’re a new RVer it may help if you have a good idea of how your RV furnace should work.
• Your RV furnace operates on the 12vdc system, You do not have to be plugged into 120v power use it.
• If your thermostat only controls the furnace and has a switch to turn the furnace on/off, switch to ON position. If your thermostat controls the furnace and the air conditioner make sure the switch is set to FURNACE.
• Set thermostat to warm temperature and furnace blower should come on after 15-30 seconds.
• The blower runs for 15-30 seconds then the burner will fire up. It’s normal for burner to cycle on and off.
• When the proper temperature is reached the burner will cut off, the blower will continue to run for a short time.
Some common RV furnace or heater problems can be solved with basic troubleshooting and simple repairs. Keep in mind that any RV furnace repair should be done by a qualified technician.
Pilot Light Won’t light or stay lit.
Make sure the thermocouple is positioned properly in the pilot flame.
Another common problem is a bad regulator at the propane tank. A simple test will indicate if this is the case. Light all the stove burners and look at the color of the flame. The flames should be blue with little or no yellow color. If the flame does not change color then the regulator is probably working. A bad regulator could also cause problems with your hot water heater.
Note: Most modern RV furnaces have a direct spark ignition system that replaces a pilot light.
The fan doesn’t run and no heat. If the fan will not start you should first check that your battery is good and you have 12 volts at the furnace. You could have a tripped circuit breaker or a blown fuse.
If the battery is good and you have electricity to the RV’s heater next check the thermostat.
Remove cover and look for the “anticipator” adjustment. (Note: Some new thermostats do not have an anticipator.) It will be an adjustable control with a sliding contact over a straight bare wire or a bare wire wound about an insulating material. If the fan will not start set the temperature to maximum and then move the anticipator slider while listening for the fan to start. Be sure to wait long enough… it normally takes our furnace 30 seconds for the fan to start once the thermostat sends a signal.
If the fan starts after you move the slider then you have probably found the problem. In this case, you may find a slider position near the original position that will work reliably. If your thermostat anticipator adjustment uses the straight wire design and the wire lies directly on the plastic housing then you should look to see if the wire has sunk into the plastic. This wire produces heat and causes the plastic to melt a little and the wire to sink into the plastic so the slider no longer makes contact. It may be necessary to replace the thermostat.
Fan runs but no heat.
If your furnace fan starts you can assume that the thermostat is working.
Possible problems are insufficient airflow through the furnace a bad propane valve at the furnace or a bad regulator at the propane tank.
A furnace contains an internal sail switch, that senses the airflow. If the airflow is not sufficient then the switch will prevent the furnace from igniting and the fan will run but you will get no heat. A slow motor speed could be caused by a low battery or other low voltage cause such as a bad connection in the wiring.
Low airflow could also be caused by a restriction in the ventilation system. Check to see if any heat registers are closed or blocked. Some furnaces will not tolerate even a partial closure of a heat register.
If you have an electronic ignition check to see if the two contacts are touching or are too far apart. They should be about 1/8 apart.
| BURNER FAILS TO IGNITE AND BLOWER FAILS TO RUN | ||
| Condition | Solution | |
| No Electrical Power to the furnace | Reconnect or replace the power source | |
| Thermostat defective | Replace thermostat | |
| Thermostat wires are broken or shorted | Replace wire or wires | |
| Circuit breaker defective or tripped | Reset circuit breaker and check amp draw from motor according to furnace’s specifications | |
| Blower relay defective | Replace relay | |
| Wire off motor or relay | Reconnect wire | |
| Bad ground | Clean and secure grounds | |
| Blower motor defective | Replace motor | |
| BURNER RUNS BUT FAILS TO IGNITE | ||
| Low voltage | Correct Power Supply | |
| Gas pressure incorrect | Set pressure to a minimum of “11” W.C. with all appliances running. Replace regulator if not obtainable. | |
| Furnace ground wires not secure | Clean and secure grounds | |
| Air intake restricted | Clean air intake | |
| Motor running slow | Correct polarity | |
| Combustion air wheel loose | Check voltage, if 12 VDC while running, replace the motor | |
| Exhaust blocked | Clean exhaust | |
| Sail switch defective | Reposition and tighten | |
| Limit switch defective | Replace switch | |
| The edge connector on circuit board dirty | Clean with a pencil eraser | |
| Circuit board defective | Clean plug contacts. If still defective, replace (check onboard tester when possible) | |
| Gas valve defective | Replace the valve or valve coil | |
| Main burner orifice blocked | Clean main burner orifice or replace | |
| High tension lead wire defective | Replace wire | |
| Electrode out of adjustment | Adjust electrode (don’t crack the porcelain) | |
| Electrode defective or cracked | Replace electrode | |
| Obstructed burner head | Clean burner head | |
| BURNER IGNITES BUT IGNITION SYSTEM | ||
| “LOCKS OUT” AND TURNS BURNER OFF | ||
| Low gas pressure | Set pressure to a minimum of “11” W.C. with all appliances running. Replace regulator if not obtainable | |
| Exhaust blocked | Clean exhaust | |
| Combustion air loose | Reposition wheel and tighten | |
| Electrodes out of adjustment | Adjust electrodes to proper specs | |
| Electrode defective | Replace electrode | |
| Circuit board defective | Clean plug contacts. If still defective, replace. | |
| Flame sensor wire between electrode and circuit board defective | Replace wire | |
| Air leakage at gaskets | Replace gasket | |
| Defective heat exchanger | Replace heat exchanger | |
| SOOTING (caused by lazy yellow flame) | ||
| Low gas pressure | Set pressure to a minimum of “11” W.C. with all appliances running. Replace regulator if not obtainable | |
| Low voltage | Correct power supply | |
| Air leakage at gaskets | Replace gaskets | |
| Combustion wheel installed backward | Reposition wheel and tighten | |
| Blockage in the heat exchanger or burner head | Clean or replace | |
| Faulty motor | Replace motor | |
| FAN RUNS CONTINUOUSLY WITH THERMOSTAT “OFF” | ||
| Defective thermostat | Replace thermostat | |
| Shorted thermostat leads | Replace wiring | |
| Defective relay | Replace relay | |
| LIMITING = BURNER CYCLING ON AND OFF | ||
| BLOWER RUNS CONSTANTLY WITH THERMOSTAT ON | ||
| Furnace over fired | Set gas pressure to a minimum of “11” W.C. with all appliances running. Replace regulator if not obtainable. Also, check the main burner orifice, it must comply with the furnace’s specifications. | |
| Restricted return air supply | Make sure return air meets furnace’s minimum requirements | |
| Restricted or insufficient discharge ducting | A) Ducting must meet minimum specifications | |
| B) No excess ducting or unnecessary bends | ||
| C) All closeable registers must be fully open and unrestricted | ||
| Defective limit switch | Replace limit switch | |
| BLOWER SHUTS OFF AT SAME TIME BURNER SHUTS OFF | ||
| Wired wrong | Correct wiring | |
| Faulty relay | Replace relay | |
| BLOWER VIBRATES OR IS NOISY | ||
| Motor mount loose | Tighten the motor mounting bracket | |
| Damaged blower wheel | Replace blower wheel | |
| Motor shaft bent | Replace blower motor | |
| INSUFFICIENT HEAT | ||
| Furnace underfired | A) Set gas pressure to “11” W.C. with all appliances running. Replace regulator if not obtainable. | |
| B) Check burner orifice. It must comply with the furnace’s specifications. | ||
| C) Check duct and return air according to furnace’s specifications. |