Newmar King Aire – Furnace Igniter & Control Board Replacement

Newmar King Aire – Furnace Igniter & Control Board Replacement

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Complete repair guide for the Newmar King Aire – Furnace Igniter & Control Board Replacement. Follow these steps to diagnose and fix the issue yourself.

Parts & Tools You’ll Need

Step 1: Diagnose Furnace Malfunction and Gather Tools

Start by confirming your furnace isn’t producing heat or is displaying ignition failure symptoms—no flame after the blower cycles on, or the burner lighting intermittently then shutting down. Gather your digital multimeter, flashlight, and all replacement parts listed above, then locate your Newmar King Aire furnace compartment, typically found in the basement or under-bed storage area. Document the current control board’s wiring configuration by taking clear photos before disconnecting anything, as you’ll need these images during reassembly.

Step 2: Shut Down Power and Isolate Propane Supply

Turn off your RV’s main 12V DC power at the battery disconnect switch and ensure the propane shut-off valve is fully closed—this is located at your propane tank or inline regulator. Wait 5 minutes for any residual gas in the lines to dissipate, then open the furnace access panel and visually inspect for any lingering flame or glow from the igniter electrode. This dual shutdown prevents electrical shock and propane-related hazards during component removal.

Step 3: Remove Old Igniter Electrode and Control Board

Locate the igniter electrode (a thin ceramic or metal rod, typically 1–2 inches long) mounted near the burner assembly and carefully disconnect its two-pin connector. Use a 1/4-inch or 5/16-inch socket wrench to unbolt the electrode from its mounting bracket, noting its exact position and angle for proper reinstallation. Next, remove the old circuit board by disconnecting all four to six color-coded wire harnesses, labeling each with masking tape (marking the terminal location), then unscrew the board from its bracket using a Phillips-head screwdriver.

Step 4: Inspect Sail Switch and High-Limit Switch Function

Before installing new components, test your existing sail switch (the vane-type sensor that confirms airflow) and high-limit switch (the thermal safety device) using your digital multimeter set to ohms mode—both should show continuity (typically 0–5 ohms) when activated. Gently move the sail switch vane by hand and confirm the multimeter reading changes; if the switch is stuck or shows infinite resistance, replace it with a new sail switch unit. These switches prevent the furnace from firing without adequate airflow and overheating, making their verification critical before reassembly.

Step 5: Install New Control Board and Reconnect Harnesses

Mount your new furnace circuit board onto the bracket, aligning the screw holes and fastening with your Phillips-head screwdriver (tighten firmly but don’t overtighten, as this can crack the board). Reconnect each color-coded wire harness to its corresponding terminal, cross-referencing your labeled photos from Step 1—the typical order is igniter (red/white), sail switch (black/green), high-limit switch (yellow/orange), and 12V power (main harness). Double-check that each connector clicks fully into place and shows no gaps, as loose connections are the leading cause of furnace malfunction after board replacement.

Step 6: Install New Igniter Electrode at Correct Angle

Position your new igniter electrode so its tip sits approximately 1/8 inch away from the burner flame path, at a 30–45 degree angle relative to the burner tube—this spacing is critical for reliable spark generation and flame sensing. Secure the electrode with your socket wrench, then reconnect the two-pin igniter connector, ensuring the pins are fully seated and the connector is tightened snugly. Verify the electrode is stable by gently pushing on it; any movement means the mounting bolt needs further tightening to prevent vibration-induced failure.

Step 7: Restore Power and Verify Safe System Operation

Reopen your propane shut-off valve and turn on the 12V DC power at the battery disconnect, then activate your furnace using the onboard thermostat and listen for the blower motor spinning up (should occur within 5–10 seconds). After 30 seconds of blower operation, you should hear the propane igniter clicking and see a visible flame near the burner assembly; the flame should remain steady for the duration of the heating cycle. Allow the furnace to run for at least 3 minutes, then use your Propane/CO combo detector alarm to confirm no leaks or unsafe combustion byproducts are present—pass the detector around all furnace fittings and exhaust vents, and verify the alarm remains silent.