RV Propane Furnace Clicks But Won't Light - Fix Guide

Tools & Parts Needed

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Quick Answer

When your Class A RV propane furnace clicks but won't ignite, you're hearing the igniter sparking but the gas isn't lighting. Common causes include issues with the igniter assembly, propane flow, air intake blockage, or control board problems. The clicking sound confirms your furnace is trying to start, which narrows down the troubleshooting significantly.

What You'll Need

• Screwdriver set (Phillips and flathead)
• Compressed air or soft brush
• Multimeter for electrical testing
• Flashlight or headlamp
• Shop vacuum (optional but helpful)
• Propane leak detector solution

Step-by-Step Troubleshooting Guide

1. Safety First: Turn off the furnace at the thermostat and shut off propane at the tank. Wait 10 minutes before beginning work to allow any accumulated gas to dissipate. WARNING: Never work on propane systems near ignition sources or if you smell gas.
2. Remove the furnace cover: Most Class A furnaces (Suburban, Dometic, Atwood) have an interior access panel. Remove screws and carefully set aside the cover.
3. Inspect the igniter: Look for the small electrode near the burner assembly. Check for corrosion, carbon buildup, or physical damage. The gap between the igniter and ground varies by manufacturer - check your owner's manual for the correct specification as this gap is critical for proper ignition.
4. Clean the igniter assembly: Use compressed air to blow away debris. Gently brush the igniter with a soft brush if needed. WARNING: Never use sandpaper or abrasives as this can damage the electrode.
5. Check propane supply: Before beginning any furnace work, test other propane appliances (stove, water heater) to verify adequate propane supply. If they work normally, propane supply likely isn't the issue. If they're sluggish or won't light, you may have low tank pressure or regulator problems that should be addressed first.
6. Examine air intake and exhaust: Go outside and check the furnace intake and exhaust vents for blockages like leaves, debris, or snow. Even partial blockages can prevent proper ignition.
7. Verify electrical operation: Before testing spark, confirm the thermostat is calling for heat and the furnace is receiving 12V power. Then with propane still off, turn on the thermostat and observe the igniter. You should see a strong blue spark. A weak yellow spark indicates igniter replacement is needed.

Most Common Causes

Dirty or Failed Igniter (60% of cases): The igniter electrode gets coated with carbon and corrosion over time, weakening the spark. This is especially common in furnaces over 3-4 years old or those used frequently.

Blocked Air Intake (25% of cases): Class A RVs often park under trees or in dusty areas. Leaves, dirt, or even spider webs in the external vents can prevent proper air circulation needed for combustion.

Propane Pressure Issues (10% of cases): Low tank levels, faulty regulators, or kinked lines can reduce gas pressure below the threshold needed for ignition, even though other appliances might still work.

Control Board Problems (5% of cases): The furnace control board manages the ignition sequence. If it's not sending proper signals or timing is off, you'll get clicking without ignition.

Brand-Specific Notes

Suburban Furnaces: Known for robust igniters but prone to air intake blockages due to lower-mounted vents. Check the sail switch (airflow proving switch) for proper operation.

Dometic Furnaces: Often have more sensitive control boards. If cleaning doesn't work, the control module may need replacement.

Atwood Furnaces: Typically have easily accessible igniters, but the electrode gap is critical - too wide or narrow prevents reliable ignition.

When to Call a Professional

Contact an RV service technician if you encounter:

• Strong propane smell during troubleshooting
• Electrical issues with the control board or wiring
• Furnace attempts to light but immediately shuts off (safety lockout)
• Multiple failed ignition attempts after cleaning
• Any uncertainty about propane system safety

WARNING: Never attempt repairs if you smell gas or suspect a propane leak. This requires immediate professional attention.

Prevention Tips

Regular maintenance prevents most ignition failures:

• Monthly: Check and clear external vents of debris
• Seasonally: Clean the igniter and inspect the burner assembly
• Annually: Have the entire propane system inspected by a certified technician
• Before storage: Run the furnace briefly to ensure it's working properly
• After storage: Test all propane appliances before your first trip

Keep spare igniters on hand - they're inexpensive insurance against breakdown in remote locations. Most RV supply stores carry universal igniters that work across brands.

Remember that furnace problems often worsen in cold weather when you need heat most. Address clicking issues promptly rather than hoping they'll resolve themselves. A well-maintained propane furnace should light reliably within 15-20 seconds of thermostat activation before safety lockout occurs.