This guide covers the complete furnace igniter and control board replacement procedure for the Grand Design Solitude – Furnace Igniter & Control Board Replacement. Follow each step carefully to restore reliable heat to your fifth wheel.
Parts & Tools You’ll Need
- Suburban/Atwood RV furnace replacement unit
- Furnace igniter electrode assembly
- Furnace sail switch
- Furnace circuit board / control board
- Furnace high-limit switch
- Furnace blower motor (12V DC)
- Propane/CO combo detector alarm
- Digital multimeter (auto-ranging)
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Step-by-Step Repair Guide
Step 1: Diagnose Furnace Failure and Disable Power
You’ll need to turn off the RV’s propane supply at the external tank valve and switch the furnace to the OFF position on your thermostat. Locate your 12V DC disconnect switch or remove the negative battery terminal to completely de-energize the furnace circuit board, which typically draws 0.5-1.2 amps during operation. Check that your Propane/CO combo detector alarm is functioning before beginning work to ensure you can detect any gas leaks during the repair process.
Step 2: Access Furnace Components Behind Water Heater
You’ll need to remove any interior cabinetry or panels blocking access to your furnace unit, which in Grand Design Solitude models is typically located near or behind the water heater compartment. Carefully disconnect the ductwork connections and remove the exterior furnace access panel by unbolting the four corner fasteners (usually 3/8-inch bolts) to expose the igniter electrode assembly and control board. Document the wire routing with photos before disconnecting any harnesses, as there are typically 4-6 wire connections to the control board that must be reconnected in their original positions.
Step 3: Remove Defective Igniter Electrode Assembly
You’ll locate the furnace igniter electrode, which resembles a small metal rod positioned near the burner opening, and disconnect its wire harness by gently pulling the weatherproof connector straight away from the electrode assembly. Unbolt the electrode bracket (typically secured with a single 1/4-inch bolt or screw) and carefully slide the assembly out, noting the precise gap spacing of 3/16-inch to 1/4-inch between the electrode tip and the burner. Store the old electrode as a reference for proper positioning of the replacement furnace igniter electrode assembly.
Step 4: Install New Furnace Igniter Electrode Assembly
You’ll insert the new furnace igniter electrode assembly into the same mounting bracket position, ensuring the electrode tip maintains the critical 3/16-inch to 1/4-inch gap from the burner primary orifice for proper spark generation. Secure the assembly with the mounting bolt and reconnect the electrode wire harness, verifying that the connector seats fully with an audible click and shows no visible corrosion on the contact pins. The replacement electrode should measure approximately 2.5-3 inches in length and feature a ceramic insulator body typical of Suburban/Atwood furnace components.
Step 5: Replace Furnace Circuit Board Control Module
You’ll disconnect all wire harnesses from the defective furnace circuit board by photographing the terminal positions and carefully removing each connector, which typically includes the thermostat signal lines, electrode igniter wires, sail switch input, and 12V DC power leads. Remove the mounting bolts (usually 2-3 quarter-inch fasteners) securing the control board to the furnace housing and slide the old board out, being careful not to disturb nearby components like the high-limit switch. Install the replacement furnace circuit board / control board in the identical position and reattach all wire harnesses to their original terminals, referencing your photos to ensure correct polarity and circuit routing.
Step 6: Verify Sail Switch and High-Limit Switch Function
You’ll use your digital multimeter set to the continuity or resistance mode (typically 200-ohm scale) to test the furnace sail switch, which should show approximately 0-10 ohms resistance when the switch paddle is in the normal position and read open (infinite resistance) when manually deflected. Check your furnace high-limit switch for similar continuity, as this safety component must open at approximately 190-200°F to prevent furnace overheating; test by measuring resistance across its terminals with the multimeter. Reinstall any access panels or ductwork connections you removed during the diagnostic phase, ensuring all fasteners are tight and no wires are pinched.
Step 7: Perform System Test and Verify Ignition Function
You’ll restore 12V DC power by reconnecting the battery terminal or flipping the disconnect switch, then set your thermostat to HEAT mode at a temperature 5 degrees above ambient and open the propane tank valve to initiate a furnace start cycle. Listen for a clicking sound from the igniter electrode (indicating proper spark generation) within 1-2 seconds of the thermostat call, then observe the burner flame igniting within 3-5 seconds; the blower motor should activate automatically after 30-45 seconds once the furnace reaches operating temperature. If the furnace doesn’t ignite after 30 seconds, immediately turn the thermostat to OFF, close the propane valve, and verify all wire connections match your diagnostic photos before attempting another test cycle.
Recommended Parts & Affiliate Links
| Part | Link |
|---|---|
| Suburban/Atwood RV furnace replacement unit | View on Amazon |
| Furnace igniter electrode assembly | View on Amazon |
| Furnace sail switch | View on Amazon |
| Furnace circuit board / control board | View on Amazon |
| Furnace high-limit switch | View on Amazon |
| Furnace blower motor (12V DC) | View on Amazon |
| Propane/CO combo detector alarm | View on Amazon |
| Digital multimeter (auto-ranging) | View on Amazon |