Most Frequent Lennox® Furnace Error Codes (and What They Mean)

December 06, 2019

While your Lennox® furnace can’t talk to you, it has a procedure to tell you about a furnace error.

Its control panel has twin LED lights that can show a fault code. Subject to the problem, your heating system could display continuous or flashing lights.

While there are certain simple HVAC adjustments you can finish yourself, most fixes are best left to the professionals. When your furnace won’t start or deliver warm air, reach out to Marcos AC & Heating at 713-469-3357 for professional furnace repair in Houston.

Our specialists will swiftly spot and repair the problem, even if you don’t have a Lennox heater. We can fix whichever brands or models—and get the warmth returned to your residence fast.


What Does the Blinking Light on My Furnace Mean?

Your heating system relies on lights to flash code when it is malfunctioning. It also works this setup to let you know it’s running properly.

Correct operation includes:

  • Concurrent slow flash—furnace operating correctly.
  • Concurrent fast flash—furnace is initiating the call for heat.

If you notice one light flashing slowly and the other blinking rapidly, your heating system could have a low flame signal. This can take place even when your heating system is heating correctly. It indicates the flame sensing rod might have build-up or in the wrong area on the burner. Contact us at 713-469-3357 for assistance.

Here are some of the most routine issues for Lennox heaters.

Furnace Will Not Start

Here are a few of the light sequences you could observe when your heat refuses to or keep operating. The bulk of these errors need to be handled by a specialist, like one from Marcos AC & Heating.

  1. The duo of LED lights are off. This signifies your furnace might not be receiving power. Examine the breaker box to confirm the heating system fuse has not triggered. Try resetting the fuse if it has moved into the “off” position. If it instantly turns off following a reset, leave the breaker alone and contact us at 713-469-3357.
  2. An individual light is unchanging and the other is flickering slowly. This signifies the flame rollout switch is possibly open. The switch is a critical safety device that helps in stopping fires and carbon monoxide. You shouldn’t attempt to take care of this issue on your own.
  3. One light is flashing rapidly and the other is flashing slowly. This often indicates power polarity has been transposed. Your heater could have a wiring error that calls for specialized support from Marcos AC & Heating.
  4. All lights are flickering slowly. This signifies your heater’s blower motor likely isn’t operating. This component circulates hot air from the furnace into your home. We can help in pinpointing what’s causing a problem with this part.
  5. One light is blinking slowly and the other is blinking fast. This signifies your HVAC system may have insufficient voltage or a short circuit. Get in touch with our technicians at 713-469-3357 for support.
  6. One light is blinking on, on and off while the other blinks on, off, on. This indicates there may be trouble with your HVAC system’s control board or wiring. Marcos AC & Heating can pinpoint the issue and repair it.
  7. Both lights are using every other slow blinks. This indicates your heating system possibly has a flame error. There could be a problem with its gas supply, gas valve or ignitor control. Call us at 713-469-3357 for assistance.
  8. A single light blinks slowly while the other stays solid. This usually signifies your HVAC system’s limit switch is experiencing an error. The switch stops your heater from getting too hot. Contact the pros at Marcos AC & Heating for help.

Furnace Blower Operates But No Heat

Here’s what may be wrong when you notice your heating system’s blower fan working, but you aren’t getting any warm air.

  • The duo of lights are showing alternate quick blinks. This means your furnace ignitor might be broken. This part ignites fuel in your HVAC equipment to produce warm air and should be fixed by an expert from Marcos AC & Heating.

Trust Us for Skilled Furnace Repair

When you need to get your HVAC equipment in working order quickly, trust the specialists at Marcos AC & Heating. Our pros will take care of the problem promptly and have your home feeling comfortable again in no time. Call us at 713-469-3357 or contact us online to get an appointment right away.