Furnace Light Blinking - What It Means

If you’re Googling why your furnace has blinking lights, you have an older furnace with an exterior light. Or you have already gone beyond what most homeowners do when their furnace is not working right. You took off the front panel. This revealed the electronic furnace control board.

Depending on the furnace make and model and the issue, you may see any of the following: 

• Furnace green light blinking continuously
• Solid/continuous green or red light
• A blinking red light on the furnace
• Solid amber or yellow light
• Error codes comprised of numbers and letters

Depending on the color of the lights, the pattern of blinking, or the error code, there might be an issue with:

• Furnace lockout
• Ignition failure
• High limit switch
• Pressure switch
• Gas valve 
• Heat exchanger
• Control board

If your furnace light blinks green, it’s not necessarily bad. Again, it will depend on your furnace's make and model what the lights mean. A slow green light blinking may mean there is simply no call for heat, while a faster green furnace light blinking continuously means the furnace is in active heating mode. 

You should not take the front panel off while your furnace is running. However, your unit may be equipped with a blower door switch which cuts power and gas to the furnace when the door is removed.

Red blinking lights on the furnace exterior or the control board, however, generally signal a problem. At this point, pay attention to the pattern of the blinking and write down what you see. It might be a steady red light blinking on the furnace or control board, or two blinks and a pause, or the furnace light blinking three times and pausing, only to repeat the sequence. Each sequence means something different.

Do not try to fix your furnace yourself. There is an electrical hazard as well as a risk of hazardous gases and explosion.

You may also see error codes in LED lights that combine letters and numbers. Write down what you see. Again, do not try to fix the furnace yourself. Not only is it hazardous for an untrained person to do so, but it can void your warranty if your furnace is still under warranty. 

If your furnace is not igniting or the furnace is not blowing hot air and you went down and took off the front panel to find a bunch of blinking lights or error codes, call for furnace repair now. Tell the person scheduling the appointment what lights or error codes you saw and the furnace brand and model (if you know it).

This will help ensure they send the right HVAC technician with the right replacement parts. When the technician arrives, they will troubleshoot, diagnose, and make the needed repairs. 

A clogged or dirty furnace filter can cause all sorts of problems. You can prevent many common issues by keeping up with air filter maintenance. This means changing standard filters every 30-90 days. If you have an air purification system, it can mean replacing the air cleaner insert every 6 months or cleaning the unit. 

Trane gas furnaces are high-quality heating systems that function best with regular maintenance checks. Schedule a yearly furnace tune-up for best results. 

Opt into Trane Diagnostics for peace of mind. Through the Trane Home App, you can give your dealer remote monitoring capabilities. Your Trane smart thermostat sends data in real-time to your dealer, alerting them to any issues, sometimes before you even realize there’s a problem. 

They can run furnace troubleshooting tests to pinpoint the problem. In some cases, they may be able to solve the problem remotely. In this situation, you would grant them one-time dealer remote access (DRA). 

If they need to schedule on-site furnace repair services, the technician will arrive with the knowledge gained from remote access. This enables shorter service calls and ensures the technician has the proper replacement parts.

Anne Fonda, Content Writer at Trane Technologies

A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism. When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

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