Suburban Furnace Not Working: Troubleshooting Guide for RV Owners

The Suburban furnace not working is a common issue for RV owners that interrupts comfort and safety. This guide explains likely causes, step-by-step troubleshooting, safety checks, and repair options to get a Suburban RV furnace running again. It focuses on practical, accurate solutions and helps decide when to repair or call a professional.

Symptom	Likely Cause	Quick Fix
Furnace Won’t Start	No power, blown fuse, thermostat issue	Check battery, fuse, and thermostat settings
Furnace Runs Then Shuts Off	Blocked vent, bad flame sensor, overheating	Inspect vents, clean sensors, check fan
Weak Or No Heat	Partial combustion, clogged burner, low propane	Check propane, clean burner assembly
Ignition Clicking But No Flame	Faulty igniter, gas valve problem	Test igniter, ensure propane flow

How Suburban RV Furnaces Work

Suburban furnaces are common in travel trailers, fifth wheels, and motorhomes. They use propane and 12V electrical power to ignite burners, produce heat, and circulate warm air with a fan. A thermostat or control board signals the furnace, which then opens a gas valve and ignites the burner using a spark or hot surface igniter. Exhaust gasses exit through a flue while intake and venting provide combustion air.

Common Symptoms And What They Mean

No Power Or No Startup

If the furnace does not respond when the thermostat calls for heat, the issue is often electrical. A dead RV battery, blown 12V fuse, or corroded wiring can prevent the furnace from receiving power. A faulty thermostat or a disconnected control wiring harness can also cause no startup.

Igniter Clicks But No Flame

Clicking without ignition usually indicates a problem with the gas supply, the igniter itself, or the gas valve. Low propane pressure, closed propane tank valves, or a malfunctioning gas control valve will prevent the burner from lighting even if the igniter is working.

Furnace Starts Then Shuts Off

When the furnace lights but shuts down quickly, common causes include blocked vents, an overheated combustion chamber, failing limit switches, or a dirty flame sensor. Blocked intake/exhaust vents are frequent culprits in winter or after storage.

Weak Heat Or Uneven Airflow

Weak heating can stem from clogged burner orifices, restricted ductwork, failing blower motor, or insufficient propane. Dirty burners and obstructions in supply ducts reduce efficiency and warm-air delivery.

Safety First: Precautions Before Troubleshooting

Always prioritize safety when working on a Suburban furnace. Turn off propane at the tank and disconnect 12V power before inspecting internal components. Ensure the RV is in a well-ventilated area when testing combustion. If gas smell is present, evacuate the RV and ventilate immediately. Use insulated tools and avoid working on the furnace with wet hands or in damp conditions.

Step-By-Step Basic Troubleshooting

1. Check Power And Fuse

Confirm the RV battery has adequate charge and the furnace is getting 12V. Inspect the furnace fuse or circuit breaker; Suburban units typically use an inline fuse. Replace blown fuses with the correct amp rating. Check for loose or corroded battery terminals.

2. Verify Thermostat And Controls

Ensure the thermostat is set to heat and the setpoint is higher than ambient temperature. For analog thermostats, test continuity with a multimeter. For digital thermostats, replace batteries if present or swap with a known working unit. Inspect wiring between thermostat and furnace for damage.

3. Inspect Propane Supply

Confirm propane tanks are open and regulator is functioning. Test other propane appliances to verify gas pressure. If multiple appliances fail, the issue is likely at the tank, regulator, or supply line. Replace an empty tank and check the tank valve and regulator for obstruction or freezing.

4. Examine Intake And Exhaust Vents

Clear snow, ice, leaves, or debris from the furnace intake and exhaust. A blocked vent prevents combustion air and triggers shutoff. Use a long brush or vacuum to remove debris. Never operate the furnace with vents blocked.

5. Check Igniter And Flame Sensor

Inspect the igniter for cracks or visible damage and ensure it produces a spark or glows if it’s a hot surface igniter. Clean the flame sensor with emery cloth or fine sandpaper if carbon buildup is present. Replace the igniter or sensor if testing shows failure.

6. Clean Burners And Orifices

Turn off propane and power, then remove the burner assembly per manufacturer instructions. Use compressed air to blow out dust and spider webs, and a small wire or needle to clear orifices. Reassemble carefully and test for proper combustion.

7. Inspect Blower Motor And Fan

Listen for unusual noises and check blower operation. Clean dust and debris from the fan blades and motor housing. Lubricate motor bearings if serviceable. A failing motor may require replacement to restore airflow.

Advanced Diagnostics And Tests

Testing The Gas Valve

Measure voltage at the gas valve while the furnace calls for heat. If the valve receives correct voltage but does not open, the valve is likely defective. Valve replacement should match Suburban part numbers and be performed with propane off and power disconnected.

Checking The Control Board

Suburban furnaces use control boards that monitor sensors and manage ignition. Inspect for burnt components, trace corrosion, or loose connectors. Reset the board by disconnecting power for several minutes. Replace the board if visible damage or persistent faults occur.

Reading Fault Codes

Many modern Suburban units flash an LED to indicate fault codes. Count flash sequences and consult the furnace manual for interpretations. Fault codes direct attention to specific issues like high-limit trips, pressure switch failures, or sensor problems.

When To Clean, When To Replace Parts

Routine cleaning—burner, sensor, vents, and blower—resolves many performance issues and should be done annually. Replace igniters, flame sensors, or control boards when tests confirm failure. Replace a worn-out blower motor or corroded gas valve. Use OEM replacement parts for compatibility and safety.

Maintenance Tips To Prevent Future Failures

• Annual Inspection: Schedule furnace inspection before cold months, including combustion tests and vent checks.
• Keep Vents Clear: Remove debris around intake and exhaust; check after storms or storage.
• Protect From Pests: Seal small openings and use vent screens to prevent spiders and insects from nesting in burners.
• Test Thermostat And Controls: Calibrate or replace faulty thermostats and verify wiring integrity.
• Battery Health: Maintain battery charge to ensure reliable 12V power during operation.

Cost Estimates And Repair Options

Costs vary by issue: simple repairs like cleaning or fuse replacement are low-cost or DIY. Replacing an igniter or flame sensor typically ranges from $30 to $150 for parts. A new control board or gas valve can be $200 to $500 plus labor. Professional diagnosis and service calls range from $100 to $300 depending on location and complexity.

When To Call A Professional

Call a certified RV technician when there is a gas leak, persistent ignition failure, suspected gas valve or control board malfunction, or if the owner lacks tools or confidence for safe repairs. Professionals can perform combustion analysis, leak checks, and ensure compliance with safety standards.

Replacement And Upgrade Considerations

When replacing a Suburban furnace, match the model size and venting configuration to the RV. Consider high-efficiency or whisper-quiet blower upgrades for comfort. Verify part compatibility, venting clearances, and installation instructions for safe operation.

Useful Tools And Parts To Keep On Hand

• Multimeter for voltage and continuity checks
• Replacement fuses and inline fuse holder
• Compressed air can or small shop vac for cleaning
• Small brushes, needle or wire for orifices
• Screwdrivers, nut drivers, insulated tools
• Replacement igniter, flame sensor, and thermostat

Resources And Where To Find Parts

Use the Suburban furnace model number on the unit label to locate manuals and OEM parts online. Reliable sources include RV parts suppliers, authorized Suburban dealers, and major RV service centers. Manufacturer manuals give wiring diagrams, fault code charts, and part lists essential for accurate repairs.

Quick Troubleshooting Checklist

1. Confirm 12V power and check furnace fuse.
2. Verify thermostat settings and wiring.
3. Ensure propane tanks are open and regulator working.
4. Clear intake and exhaust vents of debris.
5. Observe igniter operation and clean flame sensor.
6. Clean burners and check for spider webs or nests.
7. Test blower motor and airflow.
8. Read fault codes and consult the manual.

If basic steps do not restore operation, document observed symptoms and fault codes, then consult a professional to avoid unsafe DIY repairs.