Dometic Furnace Not Igniting: Troubleshooting and Fixes

The article explains practical steps to diagnose and fix a Dometic furnace not igniting issue in RVs, travel trailers, and campers. It covers likely causes, safety checks, step-by-step troubleshooting, parts and typical costs, and when to seek professional help. The goal is to give clear, actionable guidance so owners can restore heat quickly and safely.

Symptom	Likely Cause	Action
Clicking But No Flame	Igniter failure or faulty gas valve	Inspect igniter, test continuity, check gas supply
No Click, No Flame	Thermostat, control board, or power issue	Check power, fuses, thermostat, control board diagnostics
Brief Ignition Then Shutdown	Flame sensor or gas pressure problem	Clean sensor, check propane, replace regulator if needed

How A Dometic Furnace Works

Dometic furnaces used in recreational vehicles combine an electronic ignition system, a gas valve, a burner tube, and a fan. When the thermostat calls for heat, the control board sends power to the ignition assembly, opens the gas valve, and creates a spark or hot surface ignition to light the burner. A flame sensor or thermocouple confirms flame presence; the fan circulates warm air while the system runs. Understanding this sequence helps isolate the point of failure when a Dometic furnace does not ignite.

Safety Precautions Before Troubleshooting

Working with gas and electrical systems carries risk. Always turn off propane at the tank and disconnect 12V power at the battery before inspecting internal furnace components. Ventilate the area to avoid gas buildup. Use a sealed gas leak detector or liquid leak soap on fittings if gas smell is present. Wear gloves and eye protection when accessing the furnace cabinet. If uncertain about any step, stop and contact a qualified RV technician.

Common Causes Of A Dometic Furnace Not Igniting

Several issues commonly prevent ignition: faulty igniter or igniter wiring, weak or absent 12V power, blown furnace fuse or tripped breaker, malfunctioning thermostat or control board, blocked burner or ventilation, defective gas valve, low propane pressure, and a dirty flame sensor. Intermittent operation often points to failing components such as the igniter, flame sensor, or gas regulator.

Initial Quick Checks

Start with these fast inspections before deeper troubleshooting. Confirm the propane tank has adequate fuel and the tank valve is open. Verify the RV battery and 12V system are charged and supplying the furnace. Check the furnace access panel for error codes—Dometic units often flash an LED to indicate faults. Inspect the inline fuse for the furnace in the fuse panel and replace it if blown.

Step-By-Step Troubleshooting

1. Verify Power And Fuses

Ensure 12V power reaches the furnace by checking the battery voltage and RV shore/generator connections. Use a multimeter to verify 12V at the furnace connector. Inspect and replace any blown fuses. Many no-ignite problems are simply power-related.

2. Check Thermostat And Controls

Confirm the thermostat is set above room temperature and in furnace mode. Some systems have an internal relay or control board; watch for LED error codes on the board and consult the Dometic manual. Reset the furnace by disconnecting power for 30 seconds and reconnecting to clear transient faults.

3. Listen For Ignition Sounds

Activate the furnace and listen. A clicking or buzzing noise often signals the igniter is trying. No noise may indicate the igniter doesn’t get power or the control board isn’t commanding ignition. If there is a click but no ignition, suspect a faulty igniter or gas supply issue.

4. Inspect The Igniter And Flame Sensor

Access the burner area and visually inspect the igniter for cracks or damage. Use a multimeter to check igniter continuity according to Dometic specs. Clean the flame sensor with fine emery cloth or alcohol to remove soot. A dirty or failing flame sensor can cause the control board to shut the gas off quickly.

5. Verify Gas Supply And Regulator

Confirm propane is flowing by briefly opening another appliance (stove) to test pressure. A near-empty tank or closed shutoff will stop ignition. If the regulator is frozen, malfunctioning, or set too low, the furnace may not get sufficient pressure. Replace regulators that show signs of failure or age.

6. Inspect Burner And Venting

Check the burner tube and exhaust vent for blockages from insects, debris, or rust. A blocked burner or vent can prevent ignition or cause immediate shutdown. Clean or replace corroded burners and clear vents to restore normal operation.

7. Test The Gas Valve And Solenoid

The gas valve opens when the control board signals it; a defective valve or solenoid prevents flow. With safety precautions and propane shut off, inspect wiring for continuity to the valve. If the valve does not open when energized, replacement is usually required.

8. Evaluate The Control Board

The control board manages ignition sequencing. Look for burned components, corrosion, or a failed relay. Boards often indicate error codes—compare the blink patterns to Dometic documentation. If the board fails diagnostics, replacement is the next step.

Common Error Codes And What They Mean

Dometic furnaces use LED blink codes to indicate issues like failure to ignite, flame failure, or thermistor faults. Typical codes might include repeated flashes for flame failure or long flashes for thermostat issues. Consult the furnace manual for exact code interpretation and corrective actions. Recording the exact blink pattern speeds diagnosis.

When To Replace Parts

Replace the igniter if it shows visible damage or fails continuity testing. Swap the flame sensor if cleaning does not resolve flame detection issues. Replace a gas valve that won’t open or leaks. Control boards are replaced when diagnostics report internal failure or when all other components test good but ignition still fails. Use OEM Dometic replacement parts for reliable fit and performance.

Tools And Items Needed For Troubleshooting

• Multimeter for voltage and continuity checks
• Small screwdriver set and nut drivers
• Fine emery cloth and electronics cleaner
• Propane leak detector solution or spray
• Replacement fuses, igniter, flame sensor, or control board as needed

Typical Repair Costs

Costs vary by part and labor. An igniter or flame sensor replacement part ranges from $20 to $80. A gas valve or regulator typically costs $100 to $250. A control board can cost $150 to $400. Labor rates for RV technicians average $80 to $150 per hour; many owners perform these repairs themselves to save money.

Preventive Maintenance To Avoid Ignition Problems

Regular maintenance reduces ignition failures. Flush and inspect the furnace annually, clean the burner and flame sensor, check venting and seals, test igniter operation before cold seasons, and keep propane tanks full and regulators maintained. Inspect wiring for chafing and replace aged components proactively.

When To Call A Professional

Contact a certified RV technician if gas leak is suspected, if control board diagnostics exceed owner-level testing, or when the owner is uncomfortable working with propane or electrical systems. Professionals can safely pressure-test the fuel system, bench-test control modules, and perform complex repairs or warranty work.

Frequently Asked Questions

Why Does The Furnace Click But Not Light?

Clicking indicates the igniter is attempting to operate. Likely causes include a faulty igniter, weak gas pressure, a blocked burner, or a bad flame sensor preventing the board from allowing gas flow to continue.

Is It Safe To Troubleshoot A Propane Furnace?

Basic troubleshooting is safe if propane is turned off, 12V is disconnected, and work is limited to visual inspections and electrical checks. Avoid working on the gas system if a leak or strong odor exists; seek professional help.

Can A Low Battery Prevent Ignition?

Yes. Dometic furnaces require adequate 12V power to run the control board and igniter. Low battery voltage can cause clicking, incomplete ignition, or no operation at all.

How Long Do Igniters And Flame Sensors Last?

Lifespan depends on usage and environment. Igniters and sensors typically last several years but degrade with soot buildup and vibration. Inspect annually and replace when performance declines.

Resources And Manuals

Owners should download the specific Dometic furnace model manual from the Dometic website for wiring diagrams, LED error code charts, and part numbers. Manufacturer manuals provide model-specific procedures and safety warnings essential for accurate diagnosis.

Key Takeaway: Systematic troubleshooting—starting with power and propane checks, then inspecting igniter, flame sensor, burner, regulator, and control board—resolves most cases of a Dometic furnace not igniting. When in doubt, prioritize safety and consult a qualified RV technician.