Complete repair guide for the Leisure Travel Vans Unity – Furnace Igniter & Control Board Replacement. Follow these steps to diagnose and fix the issue yourself.
Parts & Tools You’ll Need
- Suburban RP-35Q 35,000 BTU/h RV Replacement Core for Suburban Furnace Series SF-35, SF-35Q, SF-42, SF-42Q, and SF-Q (2609A) — Suburban/Atwood RV furnace (replacement unit)
- Fit For Suburban RV Furnace Parts 232286,Single Probe Gas Furnace Igniters Electrode with Wire Assembly, Camper Furnace For Suburban 232286 Above 934701426 SF-20, SF-25, SF-30, SF-35 (SF Series) — Furnace igniter electrode
- DTAIR 33082 Sail Switch Replacement for Select Dometic Atwood RV Furnace(Pack of 2) — Furnace sail switch
- 520814 Rv Water Heater Module Board Ignition Control Circuit Board Compatible with Suburban Furnace SW4D, SW6D, SW6DE, SW12D, SW6DEM RV Water Heaters,Replace 520814 520820 520871 33550L (With lid) — Furnace circuit board / control board
- DTAIR 33082 Sail Switch Replacement for Select Dometic Atwood RV Furnace(Pack of 2) — Furnace high-limit switch
- Suburban 232684 RV Furnace 12v SF-Series DC Blower Motor, SF-35, SF-35F, SVF-35, SF-42, SF-42F OEM Caliber — Furnace blower motor (12V DC)
- RV Carbon Monoxide & Propane Gas Alarm, Briidea Dual LP/CO Detector with Separate LED Indicator Light, 100dB Loud Alarm, 12 VDC, Black — Propane/CO combo detector alarm
- FKM Pro Digital Multimeter Tester TRMS 6000 Counts,Smart Rechargeable Voltmeter 5″Color LCD,Auto-Ranging Automotive Multimeters,for AC/DC Current/Voltage,NCV,Ohm,Capacitance,Resistance,Continuity,Temp — Digital multimeter
Step 1: Diagnose the Furnace Failure
Start by turning off power to your RV furnace at the main breaker and allow the system to cool for at least 30 minutes. Use your digital multimeter set to DC voltage to test the furnace circuit board for proper 12V input at the power terminals—a reading below 11V indicates a power supply issue rather than a component failure. Listen for clicking sounds when you restore power; if you hear rapid clicking but no ignition flame appears within 5 seconds, this confirms either the igniter electrode or control board has failed.
Step 2: Disconnect Power and Remove Access Panel
Switch off the RV’s main electrical breaker and the propane supply valve at the tank to ensure complete safety. Remove the furnace access panel by unscrewing the four corner fasteners, then carefully disconnect the wiring harnesses from the control board by gently pulling the connectors straight out—take a photo of the connections before removal for reference during reinstallation.
Step 3: Remove the Old Control Board
Locate the furnace circuit board mounted to the side of the combustion chamber housing; it’s typically held in place with two Phillips-head screws. Carefully withdraw the board at a slight angle to clear the mounting bracket, keeping it away from the furnace interior to avoid disturbing the sail switch or high-limit switch. Set the old board aside on a clean, dry surface for comparison with your replacement unit.
Step 4: Replace the Igniter Electrode Assembly
Identify the furnace igniter electrode—a ceramic rod approximately 2 inches long with a metal tip, typically mounted near the burner tube opening. Disconnect the single spade connector from the back of the electrode, then use a wrench to remove the mounting bracket bolt. Install your replacement igniter electrode with the ceramic insulator fully seated in the bracket, ensuring the metal tip sits 3/16 inch from the burner tube opening for proper spark gap.
Step 5: Install the Replacement Control Board
Position your new furnace control board onto the mounting bracket, aligning the screw holes and securing it with the two Phillips-head screws—tighten snugly but do not over-torque. Reconnect the wiring harnesses in the exact configuration you documented before removal, ensuring each connector seats fully with an audible click. Verify that all wires are routed away from the hot surfaces of the combustion chamber and high-limit switch.
Step 6: Reconnect Propane and Restore Power
Reattach the furnace access panel with all four fasteners and ensure it sits flush. Turn the propane supply valve on at the tank, then restore power at the RV’s main breaker and set the thermostat to heat mode at 70°F to initiate a test cycle.
Step 7: Test System Operation and Verify Safety
Watch and listen as the furnace attempts ignition—you should see a bright blue flame within 5 seconds and hear the blower motor engage within 30 seconds of the ignition spark. Use your digital multimeter to confirm the control board is receiving 12V DC at the input terminals and providing proper voltage output to the igniter electrode circuit. Finally, verify your propane/CO combo detector alarm does not sound during a 10-minute heating cycle, confirming complete combustion and safe operation.