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Lennox Furnace Error Codes and how to fix them

One of the big names in the heating and cooling business for residential as well as commercial use, Lennox has been around since 1895 and Lennox Furnaces happen to be one of the company’s top-shelf products.

Lennox Furnaces have two LED lights that flash at different frequencies depending on what’s happening and if you’re wondering why one of the LEDs or both of them are flashing continuously or have been steady for long, or are worried about the blinking red light on the furnace, here we’ve listed all of the Lennox Furnace error codes, what they mean and how to fix them.

Also read: How to fix the ‘Valorant Connection Error’?

Common Lennox Furnace error codes and fixes

Following are ten of the most common Lennox Furnace error codes, why they happen, what it means and how to fix them.

Note that you might not be able to troubleshoot all of the error codes on your own. You can talk to a Lennox customer care executive on 1-800-953-6669 on Monday-Friday between 9am-7pm (EST) and ask them for a troubleshoot or to send you a technician to get the issue fixed.

Lennox Furnace Error CodesWhat it means and how to fix it
Both the LEDs are switched offThis indicates that your Lennox Furnace isn’t receiving power. You can check the furnace fuse through the breaker box and reset it if it has been tripped. If the fuse flips again, don’t try troubleshooting this Lennox Furnace issue on your own.
First LED is blinking slowly while the other is continuousThis indicates that the high limit switch is open, which is a safeguard to avoid overheating the HVAC system.
First LED is blinking slowly while the other is offThis indicates that your furnace was unable to detect gas. There might be a problem with the gas supply, valve or ignitor control. Don’t try to fix this by yourself;
First LED is off while the other is blinking slowlyThis indicates that the draft inducer is dysfunctional or else the pressure switch circuit is closed.
First and second LED are blinking slowly one at a time — alternatingThis indicates that the furnace’s flame system has failed due to a dysfunctional HVAC system, which can be caused due to an issue with the gas supply, valve or ignitor control. Don’t try to fix this by yourself; contact Lennox using the customer care number mentioned above.
First and second LED are blinking quickly one at a time — alternatingThis indicates that the furnace isn’t receiving the ideal level of voltage to function. You’ll need to check if your residence or building is receiving ample voltage or if there’s a loose connection. It’s also recommended to not use an extension to connect the furnace.

This can also mean that the furnace ignitor, which ignites the fuel, is dysfunctional. you’ll need to call an expert if this is the case.
First LED is flashing slowly while the other is blinking quicklyThis indicates that the flame level of your Lennox Furnace is low, which can happen even if the heating system on the furnace is functioning correctly. The error can be fixed by cleaning the sensing rod. If the rod is dislodged, you might want to call an expert.
First LED is flashing quickly while the other is blinking slowThis indicates that the polarity of your furnaces is reversed, which can be caused due to an issue with the wiring of the heater. Don’t try to fix this by yourself, call a technician.
Both the LEDs are blinking slowlyThis indicates that your Lennox heater’s blower motor, which moves hot air from HVAC into your living space isn’t functioning correctly. You’ll need to call an expert for fixing the issue.
One LED is blinking while the other is steadyThis indicates that the flame rollout switch on your Lennox Furnace is open. You shouldn’t try to fix this on your own as this switch is meant for your safety to avoid fires and carbon monoxide.

You can also contact Lennox via email through their contact form here.

Also read: How to fix NP-34957-8 Playstation error?

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