Armstrong Air Furnace Pilot Light Troubleshooting and Repair Guide

The Armstrong Air furnace pilot light plays a critical role in starting older gas furnaces; when it fails the system won’t heat. This guide explains how the pilot light works, common reasons it goes out, safe relighting steps, diagnostic checks, likely parts to inspect like the thermocouple and gas valve, cost and repair options, and when to call a licensed technician. Safety and accurate diagnostics are emphasized throughout.

Symptom	Probable Cause	Typical Fix
Pilot Light Won’t Stay Lit	Faulty Thermocouple, Dirty Pilot Orifice, Weak Gas Pressure	Replace Thermocouple, Clean Orifice, Check Gas Supply
Pilot Ignites But Furnace Won’t Run	Faulty Flame Sensor Or Gas Valve, Limit Switch	Inspect Flame Sensor, Test/Replace Gas Valve, Check Controls
Pilot Flickers Or Yellow Flame	Incomplete Combustion, Dirty Burner, Draft	Clean Burner, Adjust Air Shutter, Inspect Venting
Smell Of Gas Before Lighting	Gas Leak	Do Not Light; Evacuate And Call Gas Company/Technician

How The Armstrong Air Furnace Pilot Light Works

The pilot light in many Armstrong Air furnaces is a small, continuous flame that ignites the main burners when the thermostat calls for heat. In modern high-efficiency units this is often replaced by electronic ignition systems, but older models use a standing pilot. The pilot flame passes over a thermocouple or thermopile which generates a voltage to keep the gas valve open; if that signal is lost, the gas valve shuts off for safety.

Safety First: Precautions Before Troubleshooting

Turn off the thermostat and power to the furnace before any service. If there is a smell of natural gas, do not light the pilot or operate electrical switches; evacuate the home and call the gas company immediately. Only qualified personnel should perform gas line or valve repairs. Use proper ventilation, a flashlight, and avoid using matches—follow the furnace manufacturer’s relight instructions printed on the furnace access panel.

Common Reasons An Armstrong Air Pilot Light Goes Out

1. Faulty Thermocouple Or Thermopile

A worn or misaligned thermocouple is the most frequent cause of a pilot that won’t remain lit. The thermocouple senses the pilot flame and provides a small electrical current to the gas valve. When it cools or fails the gas valve closes, extinguishing the pilot.

2. Dirty Pilot Orifice Or Burner

Debris, dust, or spider webs can clog the pilot orifice and burner ports, causing a weak or unstable flame. Cleaning restores proper flame shape and heat transfer to the thermocouple.

3. Drafts Or Airflow Issues

Air drafts from gaps, nearby fans, or flue issues can blow the pilot out. Improper venting or a cracked heat exchanger location can affect combustion air and pilot stability.

4. Faulty Gas Valve Or Low Gas Pressure

If the gas valve is failing or residential gas pressure is insufficient, the pilot may light intermittently or stay weak. A technician can test line pressure and valve operation.

How To Safely Relight An Armstrong Air Furnace Pilot

Follow the manufacturer’s relight sticker or owner’s manual instructions for the specific Armstrong Air model. The following general steps describe the standard method for many standing-pilot systems.

1. Turn the thermostat to OFF and set the furnace switch to OFF; wait five minutes if you smelled gas.
2. Locate the pilot assembly on the furnace and open the access panel.
3. Turn the gas control knob to “PILOT” and depress it while holding a long-reach lighter or using the furnace’s built-in igniter.
4. Hold the button for 30–60 seconds after the pilot lights to allow the thermocouple to warm.
5. Release the knob; the pilot should remain lit. Set the control to “ON” and replace the panel; restore power and set the thermostat to call for heat.

If the pilot does not stay lit after several attempts, stop and proceed to diagnostics rather than continuing to try repeatedly.

Diagnostic Checks For Technically Inclined Homeowners

Inspect The Pilot Flame

A healthy pilot flame is a steady blue cone with a well-defined tip. A weak flame or a yellow/orange color indicates incomplete combustion or contamination. Blue Flame = Good Combustion; Yellow/Orange = Problem.

Check Thermocouple Position And Condition

The thermocouple tip must sit in the pilot flame. If bent away, loose, or covered with soot, it won’t generate proper voltage. Remove and visually inspect for corrosion; replacement is inexpensive and often resolved within 30 minutes for a competent DIYer.

Test Thermocouple Voltage

Using a multimeter on the millivolt scale, a healthy thermocouple typically produces 25–30 millivolts when heated. Significantly lower readings indicate failure. Thermopiles used in some systems produce higher voltage for electronic controls.

Examine Pilot Orifice And Burner Ports

Turn off gas and power before cleaning. Use compressed air or a fine wire to clear the orifice and burner holes. Avoid enlarging the orifice; clean gently to remove soot and debris.

Evaluate Gas Valve Function

A stuck or failing gas valve can be diagnosed by a technician who measures inlet and outlet pressure and checks solenoid operation. Homeowners should not disassemble gas valves; call a licensed tech for valve replacement or internal repairs.

Maintenance Steps To Prevent Pilot Problems

• Annual Inspection: Schedule professional furnace service before the heating season to clean burners, pilot assembly, and check controls.
• Filter Replacement: Replace air filters regularly to reduce dust that can reach the pilot assembly.
• Seal Drafts: Seal gaps near the furnace and inspect venting to prevent airflow disturbances.
• Keep Area Clean: Maintain clear space around the furnace to deter insects and debris that might clog orifices.

When The Pilot Light Is Not The Problem

If the pilot stays lit but the furnace fails to produce heat, focus shifts to other components: the gas valve, main burners, flame sensor or rollout switch. A dirty flame sensor can detect insufficient flame and shut off the burners while leaving the pilot lit. A limit switch or control board fault can also prevent burners from energizing.

Parts, Replacement Costs, And Typical Repair Times

Thermocouple replacement usually costs $15–$50 for the part and $75–$150 for labor depending on service call fees. Pilot assembly cleaning is often included in annual tune-ups at $80–$200. Gas valve replacement can range from $300–$900 including labor, varying with model and accessibility. Allow 30 minutes to two hours for most pilot light related repairs; gas valve jobs may take longer.

DIY Versus Hiring A Professional

DIY tasks that are generally safe: relighting the pilot, inspecting flame appearance, replacing a thermocouple when the homeowner is comfortable with basic tools and the furnace manual, and cleaning accessible dirt. Tasks best left to professionals: gas valve replacement, gas line inspection, pressure testing, flame sensor calibration, and internal control board diagnostics. Always comply with local codes and warranty requirements.

Model-Specific Notes For Armstrong Air Furnaces

Armstrong Air produced a range of gas furnaces; older models with standing pilot lights use similar components across model lines, while newer units often use intermittent pilot or electronic ignition systems. Verify the furnace model and serial number before ordering parts to ensure compatibility. The owner’s manual and model-specific wiring diagrams are valuable for accurate diagnostics.

Common Misconceptions And Troubleshooting Pitfalls

Myth: “If the pilot is out, the gas valve is always faulty.” Reality: Many pilot outages stem from thermocouple or orifice issues, not the valve. Myth: “Relighting repeatedly fixes everything.” Reality: Repeated attempts without addressing the root cause can be dangerous and waste time; persistent outages require inspection. Avoid over-tightening fittings or modifying orifices; that can cause hazardous conditions and violate codes.

How To Find Replacement Parts And Service

Use the furnace model number to search for OEM Armstrong Air parts through HVAC supply houses or reputable online vendors. For service, choose a licensed HVAC contractor with gas furnace experience and good local reviews. Confirm licensing, insurance, and whether the company offers written estimates and warranty on repairs.

Troubleshooting Checklist For Technicians And Homeowners

• Confirm there are no gas odors before proceeding.
• Verify pilot flame color and strength.
• Inspect thermocouple/thermopile position and measure millivolts if possible.
• Clean pilot orifice and burner ports as needed.
• Check for drafts, vent blockages, or chimney issues.
• Test the gas valve and measure line pressures if pilot issues persist.
• Inspect flame sensor and control board if burners fail to ignite.

Resources And Further Reading

Refer to the Armstrong Air owner’s manual for model-specific relighting instructions and safety warnings. The American Gas Association and local utility companies publish safety guidance on gas appliance use. For in-depth diagnostics, seek HVAC trade resources or manufacturer technical bulletins for Armstrong Air furnace parts and wiring diagrams.

Key Takeaways And Next Steps

Relighting a pilot is often straightforward but persistent problems require inspection of the thermocouple, pilot orifice, and gas valve. Prioritize safety: if gas is smelled, evacuate and call professionals. Schedule annual maintenance and use licensed technicians for gas valve or pressure work. When in doubt, stop attempts and arrange professional service to reduce risk and protect the home and occupants.

Need Immediate Help? If the furnace shows persistent failure, gas odor, or signs of carbon monoxide (headache, dizziness, stale exhaust smells), contact the gas company and a licensed HVAC technician right away.