Blinking Green Light On Furnace: Troubleshooting And Solutions

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Is your furnace showing a blinking green light? Don’t panic! It’s a common issue that many homeowners face. In this article, we will discuss the possible causes of a blinking green light on your furnace and provide you with some troubleshooting tips and solutions to resolve the problem.

Possible Causes

1. Power Interruption: A sudden power outage or surge can cause the furnace control board to malfunction, resulting in a blinking green light.

2. Faulty Thermostat: A miscommunication between the thermostat and the furnace control board can trigger the blinking green light.

3. Blocked Airflow: If the air filters, vents, or ducts are clogged or obstructed, it can lead to overheating and cause the furnace to shut down with a blinking green light.

4. Ignition Issues: Problems with the ignition system, such as a faulty pilot light or a defective igniter, can cause the furnace to enter a safety mode with a blinking green light.

Troubleshooting Steps

1. Check Power Supply: Ensure that the furnace is receiving power by checking the circuit breaker and resetting it if necessary. Also, examine the power switch on the furnace and make sure it is turned on.

2. Inspect Thermostat: Verify if the thermostat is set to the correct temperature and mode. If it has a low battery, replace it. Consider resetting the thermostat to factory settings and reprogramming it.

3. Clear Airflow Obstructions: Clean or replace dirty air filters regularly. Ensure that the vents and ducts are unobstructed and free from debris.

4. Check Ignition System: Inspect the pilot light to see if it is lit. If not, relight it according to the manufacturer’s instructions. Consider replacing a faulty igniter or seeking professional help for more complex issues.

Professional Assistance

If the troubleshooting steps mentioned above do not resolve the issue or if you are unsure about performing them yourself, it is recommended to seek professional assistance. A certified HVAC technician can diagnose the problem accurately and provide appropriate solutions.


A blinking green light on your furnace can be an indicator of various issues, ranging from minor to more significant problems. By following the troubleshooting steps mentioned in this article, you can identify and resolve the issue in many cases. However, if you are unsure or unable to fix the problem, do not hesitate to contact a professional HVAC technician for expert assistance. Remember, regular maintenance and timely repairs are essential to keep your furnace running smoothly and efficiently.