Furnace Parts

Fixing an RV furnace with the right part

Furnace troubleshooting follows the same sequence the furnace runs at startup: 12-volt power comes on, the blower spins up, the sail switch senses airflow and closes, then the board lets the gas valve and igniter fire. Find where that chain breaks and the failed part is usually obvious.

• Sail switches. The most common no-heat culprit. The blower has to move enough air to push the sail switch closed before the burner will light, a safety interlock so the furnace never fires without airflow. A stuck or misadjusted switch like the MC Enterprises 36165MC normally-closed unit stops ignition cold.
• Combustion air wheels. The Suburban combustion air wheel feeds air to the burner. Caked with dust or with bent blades, it gives you poor combustion or none at all. Match the OEM wheel to your Suburban model rather than guessing.
• Burner gaskets and service kits. The Suburban burner access gasket kit (525031) reseals the burner box after you clean or inspect it. Skip the fresh gasket and you invite a combustion leak.
• Vent caps. The exterior cap, like the Suburban 260231 twist-on, keeps weather and pests out of the exhaust. A missing or crushed cap is worth replacing before it lets water into the furnace.
• Registers. The floor and wall outlets your ducting terminates at: RV Designer's Rotaire and Provent dampered registers and JR Products steel floor registers. Dampered versions let you close off heat to a room, and the same 4-inch registers also serve A/C ducting.

Match OEM parts like the combustion wheel and gaskets to your exact Suburban or Dometic model number. If the furnace itself is past saving, the full units are in RV Furnaces, and a plug-in backup lives in Portable & Space Heaters.