Goodman Furnace Ignitor Glows but No Flame: Causes and Fixes

The article explains why a Goodman furnace ignitor glows but the burner does not light, covering common causes, troubleshooting steps, safety checks, and repair options. It provides actionable diagnostics for homeowners and tips for communicating with HVAC technicians to speed up repair. Keywords: Goodman furnace ignitor glows no flame, Goodman furnace ignitor glows but no flame, furnace troubleshooting.

Symptom	Likely Causes	Recommended Action
Ignitor glows then clicks but no flame	Gas valve/pressure issue, blocked gas line, faulty gas valve	Check gas supply, test valve, call technician
Ignitor glows continuously, no ignition	Safety limit switches, pressure switch, flame sensor dirty	Inspect switches, clean flame sensor, verify venting
Ignitor glows briefly, then goes out	Control board timing, loose wiring, weak ignitor	Check control signals and continuity

How A Goodman Furnace Ignitor System Works

Modern Goodman furnaces typically use a hot surface ignitor (HSI) or intermittent pilot that heats until it glows red and then the control board opens the gas valve for ignition. The flame sensor or rollout switches confirm combustion and allow the blower to run. The ignition sequence relies on coordinated signals: thermostat call, inducer motor run, pressure switch closure, ignitor heat, gas valve opening, flame detection, and blower activation.

Common Reasons The Ignitor Glows But There Is No Flame

1. Gas Supply Or Valve Problems

If the ignitor glows but no flame appears, the gas valve may not be opening or gas supply may be interrupted. Possible causes include a closed gas shutoff, empty propane tank, or a failing gas valve. Even when the valve receives a signal, internal failure can prevent gas flow.

2. Pressure Switch Or Inducer Motor Issues

The inducer motor and pressure switch verify proper venting before the gas valve is allowed to open. If the pressure switch does not close, the control board will keep the gas valve shut even though the ignitor glows. A clogged vent or failing inducer motor often causes this failure.

3. Faulty Control Board Or Sequencing Error

The control board orchestrates timing for ignitor heat and gas valve activation. A bad relay, weak output, or failed sensor input can lead to the ignitor glowing without the gas valve receiving the signal to open. Intermittent electronics faults produce inconsistent ignition behavior.

4. Flame Sensor Or Ignition Verification Fault

A dirty or malfunctioning flame sensor can prevent the system from detecting a flame, causing the control board to shut the gas valve quickly or prevent it from opening on repeat cycles. Though the ignitor glows, the board may lock out the ignition sequence after a failed sense attempt.

5. Mechanical Or Obstructed Gas Line

Obstructions, closed valves, debris, or a kinked supply line restrict gas flow. Even partial blockages can allow the ignitor to glow while preventing sufficient gas to produce a stable flame. Professional pressure testing is required to confirm line integrity.

Troubleshooting Steps Homeowners Can Safely Perform

Safety First

Before any inspection, turn off power to the furnace at the breaker and shut off the gas at the appliance if working on gas lines. If a gas odor is present, evacuate the home and call the gas utility immediately. When in doubt, contact a licensed HVAC technician or gas professional.

Visual Checks And Simple Actions

• Confirm thermostat calls for heat and settings are correct.
• Verify the furnace switch and circuit breaker are on and not tripped.
• Look for error codes or LED blink patterns on the furnace control board; record code sequence for technician reference.
• Inspect the vent and exhaust for visible blockages like bird nests or debris.

Check The Gas Supply

Ensure the gas shutoff valve near the furnace is open. For homes with meters or propane tanks, confirm service is active. If the homeowner has a gas cooktop or water heater, verify those appliances are receiving gas to isolate the issue to the furnace.

Listen And Observe The Ignition Sequence

With the cover on, turn power back on and cycle the thermostat while listening. Note the following: the inducer starts, the ignitor glows, a clicking or valve sound indicates the gas valve attempting to open, and then flame should appear. Timing and order help identify where the sequence fails.

Diagnostic Tests For Technicians Or Experienced DIYers

Test The Gas Valve

A multimeter can verify control voltage across the gas valve terminals during the call for heat; typical valve voltage is 24 VAC. Absence of 24 VAC indicates control board or transformer issue. Presence of 24 VAC with no gas flow suggests a stuck valve requiring replacement.

Check The Pressure Switch And Inducer

Measure continuity across the pressure switch when the inducer runs. If the switch does not close, inspect tubing for blockages and test inducer motor operation. A restricted flue or failed inducer may prevent pressure switch closure and gas valve activation.

Inspect The Flame Sensor And Ignitor Condition

Remove and clean the flame sensor with fine emery cloth or steel wool; a coated sensor causes false negatives. Inspect the ignitor for cracks or erosion; a visibly fragile or partially cracked HSI may glow but not reach required surface temperature to ignite gas reliably.

Evaluate Control Board And Safety Switches

Observe LED diagnostic codes, test relays and transformers, and verify wiring harness integrity. Check limit switches, rollout switches, and door interlocks that can prevent valve activation. Intermittent loose connectors can cause sporadic no-flame conditions even though the ignitor glows.

When Professional Repair Or Replacement Is Necessary

If the gas valve is defective, the control board malfunctions, inducer motor fails, or there is a suspected gas leak, a licensed HVAC technician should perform repairs. Replacing safety-critical components or handling gas connections requires certification and proper tools.

Common Parts That May Require Replacement

• Gas valve (24 VAC gas control valve)
• Control board or relay module
• Inducer motor or pressure switch
• Hot surface ignitor (HSI) or flame sensor
• Venting or heat exchanger repairs if corrosion or blockage exists

Cost Considerations And Repair Timeline

Repair costs vary by region and part. Typical ranges: ignitor replacement $100–$300, flame sensor cleaning or replacement $75–$200, gas valve replacement $300–$800, control board $200–$700, inducer motor $200–$600. Emergency or after-hours service increases costs. Accurate diagnosis often requires a service call fee.

Preventive Maintenance To Avoid Ignitor-Glows-No-Flame Issues

Annual furnace tune-ups reduce ignition failures. Recommended tasks include cleaning burners and flame sensors, checking gas pressure and valve operation, inspecting venting and condensate drains, verifying inducer operation, and testing safety switches. Replacing filters regularly improves airflow and reduces flame instability.

How To Communicate Effectively With An HVAC Technician

Provide specific observations: the ignitor glows but no flame, any LED error codes, smells of gas, recent service history, and whether other gas appliances are working. Note the sequence heard during start-up and whether the condition is intermittent or constant. Clear details help technicians bring the correct parts and speed diagnosis.

When To Shut Down The Furnace And Evacuate

If a strong gas smell is present, light-headedness occurs, or a physical leak is suspected, leave the house immediately and call the gas utility or emergency services. Do not operate electrical switches or appliances that could produce sparks. Safety trumps troubleshooting when the presence of gas persists.

Key Takeaways And Quick Troubleshooting Checklist

• Confirm gas supply and that other gas appliances function.
• Check venting and inducer operation—blocked venting often stops the gas valve despite an ignitor glow.
• Record control board error codes for faster diagnosis.
• Clean the flame sensor as a low-cost first step.
• Do not attempt gas valve replacement without a licensed technician.

Additional Resources And Manufacturer Guidance

Goodman publishes technical data sheets, wiring diagrams, and error code guides relevant to specific furnace models. For accurate part numbers and service instructions, reference the furnace model plate or the Goodman dealer network. Many service manuals include startup sequence charts that clarify expected timing between ignitor glow and gas valve activation.

For safety, homeowners should rely on certified HVAC professionals for gas-related repairs and complex electrical diagnostics. Proper maintenance and timely repairs ensure reliable heating and safer operation.