How to Troubleshoot a Mobile Duo Therm Furnace

Locate the circuit breaker box to your recreational vehicle, if the Duo Therm furnace fails to power on. Open the box door and locate the circuit breaker that controls the furnace. Inspect the state of the circuit breaker switch; if the switch is in the middle or “Off” position, the breaker is tripped and the furnace receives no power. Flip the switch to the “On” position to close the electrical circuit to the furnace and restore power.

Turn off all appliances inside of the RV, if the Duo Therm doesn’t receive power, fuses are blown and you suspect a short circuit problem. Install an amperage meter onto the positive terminal of the vehicle battery. Remove the electrical panel cover from the furnace and remove the vehicle battery’s red direct current wire from the furnace power terminal. If the amperage meter receives no amperage reading, the furnace has an internal electrical problem. Contact Duo Therm or a technician for repair.

Locate the gas valve, which controls the gas flow from the gas source to the Duo Therm, and confirm that the valve is completely open. Twist the valve clockwise or to the right to close it, then counterclockwise or to the left to open it again. Contact a technician, if you suspect a leak.

Remove the cabinet from the furnace to access the fan motor, if the Duo Therm runs but fails to blow. Inspect the fan housing for complications, such as a burned up motor or an improperly installed fan component. If the fan is installed incorrectly, the blades might not be able to turn freely within the housing, keeping them from blowing. Uninstall the fan and reinstall it correctly, so that it doesn’t strike the housing. Replace the fan motor, if it’s burned up.

Remove the electrical panel cover from the unit, if the Duo Therm cuts in and out erratically. A wire might not be properly secured on the terminal panel. Inspect all wired terminals and confirm that the wires are securely connected. Tighten all wires into the terminals, if necessary, and reactivate the furnace.