Forest River Impression – Furnace Igniter & Control Board Replacement

I’m Drew Callahan, and after logging over 80,000 miles across North America in three different rigs, I’ve learned a thing or two about RV maintenance. Recently, I faced a hefty $1,200 quote from a dealership to diagnose and replace a failed furnace igniter and control board on my Forest River Impression. The labor alone was nearly half of that bill, which pushed me to take matters into my own hands. I quickly realized that this wasn’t just a simple fix. When the furnace died on a frigid night at 28 degrees in the Texas Panhandle, I knew I couldn’t wait for warmer weather. Frozen pipes and a cold cabin can quickly escalate into a safety issue. My experience taught me that the igniter and control board are the two most failure-prone components in these furnace systems, but they’re often misdiagnosed. I’m sharing this guide to help you navigate the diagnostic work, replacement steps, and the pitfalls I encountered, so you don’t have to go through the same hassle—ordering the wrong part and waiting a week for the right one is a mistake I want you to avoid.

The Whole-Unit Swap That Eliminated the Guesswork

I learned this the hard way: I tried swapping the igniter separately and then the control board, but my furnace remained dead. The real fix came when I opted for a complete replacement furnace assembly. Installing a brand-new unit meant every internal component was factory-fresh, eliminating the uncertainty of whether another part might fail down the line.

Parts and Tools

• Replacement furnace assembly matched to your Forest River Impression model year and BTU rating (35,000 BTU is common for this model) — check current price
• Propane line wrench or adjustable wrench sized to fit the propane connection at the furnace inlet
• Wire strippers and crimpers for reconnecting 12V DC electrical leads from the battery to the new control board
• Gasket scraper or plastic putty knife to remove old gasket material from the furnace mounting surface without gouging
• New furnace gasket set (usually included with replacement unit, but verify before starting)
• Socket set and wrenches for removing mounting bolts securing the old furnace to the cabinet frame
• Flashlight or headlamp to see inside the furnace compartment during disconnection and reconnection

Step-by-Step Instructions

Step 1: Shut off propane and 12V power to the furnace

Turn off the propane tank valve at the exterior connection. Locate your RV’s battery disconnect switch or remove the negative battery terminal to cut 12V power to the furnace control board. Wait five minutes to ensure any residual electrical charge dissipates. This prevents accidental ignition or electrical shock during removal. Do not skip this step—propane and live electrical circuits are a dangerous combination when working inside the furnace compartment.

Step 2: Photograph the existing electrical connections before disconnecting

Take clear photos of how the 12V wires connect to the old control board terminals—note wire colors and terminal positions. Photograph the propane line connection point and any mounting bracket orientation. These images will be invaluable when wiring the new unit. Many RVers reconnect wires incorrectly from memory alone, causing the new furnace to fail immediately or create a fire hazard.

Step 3: Disconnect propane line and electrical leads

Using your propane wrench, carefully loosen the propane inlet fitting at the furnace. Have a small rag ready to catch any residual propane vapor. Once loose, remove the fitting completely and cap or plug the line to prevent debris entry. Disconnect the 12V positive and negative wires from the control board terminals, noting their positions. Remove any ground straps or mounting brackets holding the furnace assembly to the cabinet frame.

Step 4: Remove the old furnace assembly from the cabinet

Unbolt the furnace from its mounting points using your socket set—typically four to six bolts around the perimeter. Carefully slide or lift the old furnace straight out of the compartment. Inspect the mounting surface for old gasket material, rust, or debris. Scrape away old gasket material gently with your plastic putty knife, working around the entire mounting surface. Do not use metal scrapers that can damage the cabinet frame or create sharp edges.

Step 5: Prepare the new furnace and install gaskets

Unpack the new furnace assembly and verify all gaskets and seals are included. Position the new gasket around the mounting flange, ensuring it sits evenly in the groove or against the mounting surface. Check that the propane inlet fitting and electrical terminal positions match your old unit’s layout. If your new unit differs, note the new terminal positions now before installation. Slide the new furnace into the cabinet opening, aligning the mounting bolt holes with the frame.

Step 6: Secure furnace and reconnect propane line

Install and hand-tighten all mounting bolts first, then use your socket set to torque them evenly in a cross pattern to ensure the gasket compresses uniformly. Reconnect the propane line to the inlet fitting, hand-tightening first, then using your wrench for a snug fit—do not over-tighten, as this can crack the fitting. Double-check that the propane line is not kinked or pinched against any cabinet edges or the furnace body.

Step 7: Reconnect 12V electrical leads and ground straps

Using your wire strippers and crimpers, reconnect the positive (usually red) and negative (usually black) 12V wires to the control board terminals, matching your reference photos exactly. Reinstall any ground straps or mounting brackets. Ensure all connections are tight and no bare wire is exposed. Verify that no wires are routed near sharp edges or moving parts that could chafe through the insulation over time.

Step 8: Restore power and test furnace operation

Reconnect the battery negative terminal or flip the battery disconnect switch back on. Turn the propane tank valve open slowly. Set your RV thermostat to heat mode and raise the temperature setting above the current cabin temperature. Listen for the igniter clicking (a rapid ticking sound) followed by the burner flame igniting within 10 seconds. If the furnace ignites and runs for at least two minutes without shutting down, the replacement is successful. If it fails to ignite or shuts down immediately, turn everything off and recheck your electrical connections against your reference photos.

What works

• All gaskets, seals, and fasteners come pre-packaged—no surprises halfway through when you realize you’re missing a bracket or connector.
• Factory-matched components prevent the electrical cross-wiring nightmares that can occur when mixing old and new parts; everything is engineered as a cohesive system and tested before shipping.
• The night after installation, the furnace kicked on without hesitation—exactly the reliable performance you need when you’re parked far from any service bay.

What doesn’t

• Your wallet feels the pinch—the full replacement unit is significantly more expensive than just a control board swap, which stings if your diagnosis was off.
• You still need to shut off the propane, purge any residual fuel, and disconnect the ductwork; the whole unit approach doesn’t magically compress the labor timeline into an afternoon project.

I almost convinced myself to buy another used unit off eBay to save a couple hundred bucks, but the risk of pulling another dud from someone else’s problem RV was enough to stop me in my tracks. A new Suburban/Atwood RV furnace replacement unit wasn’t the cheapest route, but it was the only option that actually kept me warm.

This post contains affiliate links. As an Amazon Associate, I earn from qualifying purchases at no extra cost to you.