Heil Furnace Troubleshooting

Is your Heil furnace not functioning as it should be? It may be time to troubleshoot some of the most common issues that the gas furnace is experiencing. And no, not all issues call for an HVAC guy to fix it; you can take care of several issues all by yourself.

However, that’s not to say you should be doing everything yourself – many issues are too complicated for homeowners to fix easily. But more on that later. Let’s look at the common issues first and how to troubleshoot them yourself.

Common Issues and How to Troubleshoot Heil Furnaces

  • Issue: The furnace does not heat.
  • How to troubleshoot:
    • Examine the igniter for any visible signs of damage or discoloration, noting that a functioning igniter typically emits a bright orange glow.
    • Conduct a continuity test using a multimeter. A lack of continuity indicates that the igniter needs to be replaced.
    • Handle the igniter gently during inspection to prevent any accidental breakage.
  • Issue: The furnace fails to ignite or heat properly.

  • How to troubleshoot:

    • Check that the gas control valve is open and that there is a continuous supply of gas.

    • Utilize a manometer to measure the gas pressure, ensuring it meets the specified requirements for your model (around 4 inches of water column for natural gas).

    • Inspect the gas line for any obstructions or leaks that might impede gas flow.

  • Issue: The furnace is unresponsive or doesn't turn on.

  • How to troubleshoot:

    • Check for a steady indicator light on the control board to verify if power is reaching the furnace.

    • Inspect your home’s electrical panel for any tripped breakers or blown fuses and address as needed.

    • Ensure that the furnace's external power switch is in the "on" position and is securely connected.

  • Issue: The furnace starts but shuts down soon after.

  • How to troubleshoot:

    • Remove and clean the flame sensor with a fine abrasive pad to eliminate any residue that might prevent it from detecting a flame.

    • Test the flame sensor for continuity using a multimeter. Replace the sensor if it does not pass this test.

  • Issue: The furnace stops working shortly after starting, or fails to exhaust air properly.

  • How to troubleshoot:

    • Listen for any unusual sounds from the exhaust motor, or check if it's operating silently, which could indicate a problem.

    • Check for any blockages in the fan or exhaust pipe of the inducer motor that could restrict airflow.

    • Use a multimeter to check for electrical continuity in the motor. Consider replacing the motor if it fails this test.

  • Issue: The furnace frequently cycles on and off.

  • How to troubleshoot:

    • Examine the pressure switch hose for any signs of wear or damage that might affect its ability to detect pressure changes.

    • Ensure that the hose and the port on the inducer assembly are free from clogs.

    • Test the pressure switch with a multimeter to confirm it closes at the correct pressure levels. Replace if necessary.

  • Issue: The furnace behaves erratically or does not respond to controls.

  • How to troubleshoot:

    • Look over the control board for any signs of damage or burnt components.

    • Use a multimeter to check the functionality of relays and the correctness of voltage outputs.

    • If the control board appears to be faulty or damaged, replacing it might be necessary.

  • Issue: Room temperature is inconsistently regulated, affecting furnace operation.

  • How to troubleshoot:

    • Ensure the thermostat is properly set and calibrated to prompt furnace operation.

    • If the display is unresponsive, replace the batteries.

    • Conduct a continuity check with a multimeter. A failed test of the thermostat calls for a replacement.

  • How to troubleshoot:

    • Change the air filter regularly—every few months or more often in dusty environments or homes with pets.

    • Make sure all vents and registers in the home are open and unobstructed to maintain effective airflow.

Understanding Error Codes and Indicator Lights

Error codes on a Heil furnace are communicated through a series of LED flashes on the control board, helping users identify specific operational issues. Let’s look at the error codes:-

LED Flash Patterns and What They Signify

1. LED flashing like a heartbeat

  • Meaning: The control has 24 VAC power.

  • Recommended Response: This is a standard status indicating that power is properly supplied to the control board; no further action is required unless additional codes are displayed.

2. Two LED flashes

  • Meaning: The unit’s pressure switch didn’t open.

  • Recommended Response: Inspect for an obstruction in the pressure tubing. Verify the functionality of the inducer motor and ensure no blockages are affecting the airflow.

3. Three LED flashes

  • Meaning: The unit’s pressure switch didn’t close or has reopened.

  • Recommended Response: Possible causes include excessive wind, improper vent size, malfunctioning inducer motor, defective pressure switch, insufficient combustion air supply, or disconnected or blocked pressure tubing. Investigate these elements and resolve any discrepancies.

4. Four LED flashes

  • Meaning: Limit circuit fault; either a limit or flame rollout switch is open.

  • Recommended Response: Investigate for issues such as a restricted vent, unsecured blower wheel, high wind conditions, a clogged air filter, or a malfunctioning blower. Rectify any problems to restore functionality.

5. Five LED flashes

  • Meaning: An abnormal flame proving signal; the flame is detected while the gas valve is de-energized.

  • Recommended Response: Examine for a leaky gas valve or a gas valve that remains open. This condition typically necessitates a professional evaluation and repair.

6. Six LED flashes

  • Meaning: Failure to ignite or loss of flame sensor signal during operation.

  • Recommended Response: Examine components such as an improperly grounded flame sensor, faulty hot surface ignitor, issues with control ground continuity, inadequate flame carryover, or rough ignition. Address the identified issue specifically.

7. Seven LED flashes

  • Meaning: Limit circuit lockout.

  • Recommended Response: This lockout occurs if the limit or flame rollout switch remains open for more than 3 minutes. The control will automatically reset after 3 hours. Assess the airflow and component operation to pinpoint the root cause.

8. Eight LED flashes

  • Meaning: Gas heating lockout; the control will not auto-reset.

  • Recommended Response: Inspect for incorrect wiring of the gas valve or a faulty control valve. This severe issue often requires intervention from a professional technician.

9. Ten LED flashes

  • Meaning: Polarity reversal detected.

  • Recommended Response: Consult installation instructions to correct any polarity issues, ensuring all electrical connections are accurate.


Additional Error Code Combinations

1 + 2 LED flashes

  • Meaning: Blower is active post power-up.

  • Recommended Response: This occurs if the unit powers up during a heat call or opens while the blower is on delay.

6 + 1 LED flashes

  • Meaning: Ignition lockout.

  • Recommended Response: The control will reset after 3 hours. Ensure proper ignition processes are followed and check for faults.

LED Status Indicators

LED is off

  • Meaning: The secondary voltage fuse is open.

  • Recommended Response: Verify the door switch is closed or look for a short circuit. Replace the fuse if necessary.

LED is on

  • Meaning: Control circuitry lockout.

  • Recommended Response: Will reset automatically after 1 hour. If the problem continues, reset power to clear the lockout and consider replacing the control if the status code recurs.

LED is solid

  • Meaning: Issues with gas valve relay, flame sense circuit, or software error.

  • Recommended Response: Reset power to clear the lockout and replace the control if the error persists.

Note icon | Comfort Union

Furnace Troubleshooting Guides

Our comprehensive troubleshooting guide offers step-by-step solutions to common issues. From heating failures to airflow problems, we've got you covered."

Should you call an HVAC professional? When should you call?

Maintaining an efficient and reliable HVAC system is crucial for the comfort and safety of your home. While some problems might be solvable through straightforward troubleshooting, there are instances where professional expertise is much needed. Here are tips from Comfort Union, a leader in HVAC solutions, on when to call for help from a professional:

  1. Persistent Issues

Repeatedly addressing the same HVAC issue might indicate underlying complexities that require expert diagnosis and a more durable solution.

  1. Lack of Heat or Irregular Heating Performance

If your furnace ceases to produce heat or operates inconsistently, this could point to major issues such as malfunctioning ignition systems or a compromised heat exchanger, necessitating professional repair for safety and efficiency.

  1. Seeking Enhanced Energy Efficiency

An unexpected rise in energy bills, despite usual usage patterns, suggests that your heating system may not be operating efficiently. A professional evaluation can help homeowners get recommendations for repairs or updates that enhance efficiency and lower operating costs.

  1. Scheduled Annual Maintenance

Regular, professional maintenance is recommended to extend the lifespan of your HVAC system and ensure it operates at peak efficiency. This preventive measure can help avoid unforeseen issues.

  1. When Installing, Upgrading, or Undertaking Major Repairs

If you need new systems installed in your house, or you want significant upgrades or major repairs – it should always be conducted by professionals. These processes require specific skills and tools to ensure safety and compliance with local regulations.

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Why Opt for Comfort Union?

Comfort Union is renowned for its team of certified, experienced technicians capable of handling all facets of HVAC maintenance and repair. Committed to excellence and customer satisfaction, Comfort Union ensures reliable service and professional guidance.

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