Dometic Furnace Reset Switch

Why The Reset Switch Trips

The reset switch trips for several legitimate reasons. Awareness of these causes helps diagnose whether the problem is electrical, mechanical, or environmental.

• Overheating: Restricted exhaust, blocked intake, clogged combustion air paths, or a failed blower motor can raise temperatures and trigger the switch.
• Electrical Faults: Shorts, reversed polarity, damaged wiring, or a failing control board may cause excessive current draw that trips the switch.
• Component Failure: A bad thermostat, gas valve, or blower can create abnormal operating conditions that lead to a trip.
• Environmental Factors: Snow, debris, insects, or external heat sources near the furnace can cause overheating or disruption of combustion air.

Safety First: Before Troubleshooting

Safety is paramount. The reset switch is a protective device; repeatedly bypassing or ignoring it can create fire or carbon monoxide risks. Follow these safety checks before any inspection or repair.

• Turn off power at the battery disconnect or shore power breaker and disconnect propane when applicable.
• Work in a well-ventilated area and avoid inhaling dust or debris.
• Wear gloves and eye protection when handling sharp sheet metal or corroded terminals.
• If any smell of gas or suspected leak exists, evacuate and contact a qualified service technician immediately.

Step-By-Step Troubleshooting

The following sequential checks progress from simple to more advanced diagnostics. Proceed methodically and stop if a problem appears beyond personal skill or tools.

Visual Inspection

Inspect the furnace exterior for dents, corrosion, signs of heat damage, or insect nests. Check the flue and fresh air intake openings for blockages and clear any debris. Look for water intrusion or rusted fasteners that may indicate leaks.

Check Power And Fuses

Confirm the RV or boat battery has sufficient charge and that the furnace fuse or breaker is intact. Dometic furnaces commonly use a 10–20 amp inline fuse; consult the furnace manual for the exact rating. Replace blown fuses with the correct type and rating only.

Test The Reset Switch

Locate the reset switch and visually inspect it for burning or melting. Use a multimeter to test continuity with power off. If the switch shows no continuity in the resting state or cannot be reset, it should be replaced.

Inspect Blower And Motor

Remove the access panel to access the blower. Spin the blower wheel by hand to check for free rotation and any rubbing noise. Measure motor current with an ammeter if available; excessive current draw indicates a failing motor or blocked airflow.

Airflow And Combustion Path

Verify that supply vents, return ducts, and the combustion air intake are clear. Clean furnace air filters and remove obstructions from the flue outlet. Restricted airflow is a frequent cause of overheating and reset trips.

Control Board And Wiring

Inspect control board connectors and harnesses for loose pins, corrosion, or melted insulation. Gently wiggle connectors while observing operation to detect intermittent faults. Repair or replace damaged wiring using correct gauge and temperature-rated wire.

Gas System Checks

For propane-fired furnaces, confirm the propane supply, regulator operation, and gas valve function. Listen for the valve click when the thermostat calls for heat. If the furnace smells strongly of propane at any time, stop and have a certified RV technician inspect the system.

When To Replace The Reset Switch

Replacement is necessary when the switch fails to reset, shows visible damage, or fails continuity testing. Using the exact OEM-style replacement is recommended because different switches have varying trip characteristics and current ratings.

Replacement steps typically include disconnecting power, removing the old switch, transferring wiring, installing the new switch, and testing operation. If wiring terminals are corroded, replace them and use dielectric grease to prevent future corrosion.

OEM Parts And Aftermarket Options

OEM Dometic reset switches or assemblies are preferable for fit and function. Aftermarket switches can be acceptable if they match the electrical specifications, mounting dimensions, and safety standards.

Part Type	Pros	Cons
OEM Dometic Switch	Guaranteed compatibility, correct ratings	May be more expensive, limited availability
Equivalent Aftermarket Switch	Often lower cost, easier to source	Risk of mismatched specs, reduced durability

Tools And Materials For Safe Repair

Basic tools and supplies include a multimeter, insulated screwdrivers, wire cutters/strippers, replacement fuse, replacement reset switch, dielectric grease, terminal crimpers, and an ammeter for motor current testing if available.

For gas system repairs or complex electrical diagnostics, a certified RV technician or licensed propane technician is recommended to ensure compliance with safety codes and warranty requirements.

Preventive Maintenance To Avoid Trips

Regular maintenance reduces the likelihood of reset switch trips and extends furnace life. Key tasks include cleaning vents and flues seasonally, inspecting and cleaning blower assemblies, tightening electrical connections yearly, and checking for water intrusion around the furnace compartment.

• Seasonal Checks: Clean exterior vents and remove wasp nests or debris.
• Annual Service: Inspect and lubricate moving parts, replace fuses, and test safety devices.
• Battery Maintenance: Keep house batteries charged and connections clean to avoid low-voltage conditions that stress the furnace control.

When To Call A Professional

Professional service is advised when the fault involves the gas valve, major wiring harnesses, control board replacement, persistent overheating after airflow correction, or when a gas leak is suspected. Licensed technicians have pressure-testing tools, combustion analyzers, and access to OEM diagnostics.

Frequently Asked Questions

Can The Reset Switch Be Bypassed?

The reset switch should never be bypassed. Bypassing removes a primary safety control and significantly increases fire and carbon monoxide risks. Repair or replacement is the correct course.

How Many Times Can The Switch Be Reset?

There is no fixed number; frequent resets indicate an unresolved problem. Resetting a few times during a controlled diagnosis is acceptable, but repeated trips require investigation and repair.

What If The Furnace Still Does Not Work After Reset?

If the furnace does not operate after resetting the switch and verifying power, further diagnostics on the thermostat, control board, and gas valve are necessary. Trace voltage to components and consult wiring diagrams or a technician.

Key Troubleshooting Checklist

1. Confirm power source and fuses are good.
2. Visually inspect reset switch for damage.
3. Clear vents and flue from obstructions.
4. Test blower motor for free spin and normal current draw.
5. Check wiring for corrosion, loose terminals, and proper insulation.
6. Replace the reset switch with an OEM or spec-matching part if faulty.
7. Call a qualified technician for gas, control board, or persistent overheating issues.

Resources And Manuals

Owners should keep the furnace owner’s manual and wiring diagrams accessible. Dometic publishes technical manuals and parts diagrams on its website and via authorized dealers. For propane system questions, reference the National Propane Gas Association guidance and local codes.

Replacement parts may be purchased from Dometic dealers, RV parts suppliers, or reputable online retailers; confirm part numbers and compatibility before purchase.

Summary Of Best Practices

Maintain clear airflow, use the correctly rated fuse and replacement switch, never bypass the reset switch, and address overheating causes promptly. Regular inspections and adherence to safety protocols will minimize trips and ensure reliable heating performance in RVs and marine applications.