Top Lennox® Furnace Error Codes (and What They Mean)


While your Lennox® heater cannot speak to you, it possesses a procedure to communicate a furnace error.

Its motherboard has double LED lights that can share a fault code. Subject to the problem, your heater could display steady or flashing lights.

Though there are a few basic furnace fixes you can complete on your own, most repairs are best left to experts. When your heating system will not start or provide warm air, reach out to Air Houston Mechanical LLC at (832) 501-3419 for experienced furnace repair in Huffman.

Our technicians will speedily detect and repair the malfunction, even if you don’t use a Lennox heater. We can repair any brands or makes—and get the warmth restored to your house fast.

What Does the Blinking Light on My Heater Mean?

Your heating system relies on lights to flash code when it needs to be repaired. It also engages these lights to relay its heating as it should.

Normal heating involves:

  • Simultaneous slow flash—heating system operating as it should.
  • Both lights flash fast—the furnace is beginning to call for heat.

If you notice a single light blinking slowly and the other flashing rapidly, your heater could be having a low flame signal. This can happen even when your furnace is running as it should. It indicates the flame-sensing rod might be dirty or in a bad spot on the burner. Reach out to us at (832) 501-3419 for help.

Here are some of the most typical faults for Lennox heating systems.

Heating System Won’t Kick On

Here are many of the light patterns you could see when your heater won’t turn on or keep heating. The bulk of these issues must be taken care of by a professional, for instance from Air Houston Mechanical LLC.

  • All LED lights are off. This means your heater might not have power. Go to the breaker box to make sure the heater fuse has not tripped. You should reset the fuse if it’s in the “off” area. If it promptly flips after a subsequent reset, leave the breaker alone and contact us at (832) 501-3419.
  • One light is stable and the other is blinking slowly. This implies the flame rollout switch may be open. The part is a critical safety mechanism that assists in avoiding fires and carbon monoxide. You shouldn’t seek to take care of this fault without professional help.
  • A single light is flashing rapidly and the other is flashing slowly. This often signifies power polarity has been reversed. Your heating system might have a wiring issue that calls for expert help from Air Houston Mechanical LLC.
  • Both lights are flashing slowly. This signifies your furnace’s blower motor likely isn’t running. This part circulates hot air from the furnace into your house. We can assist in pinpointing what’s wrong with this part.
  • An individual light is blinking slowly and the other is blinking fast. This indicates your HVAC system may have not enough voltage or a short circuit. Reach out to our professionals at (832) 501-3419 for support.
    One light is flickering on, on, and off while the other flickers on, off, and on. This indicates there could be an issue with your heating system’s motherboard or wiring. Air Houston Mechanical LLC can pinpoint the problem and take care of it.
  • Both lights show alternate slow flashes. This means your HVAC equipment may have a flame issue. There might be a problem with its gas supply, gas valve, or ignitor control. Get in touch with us at (832) 501-3419 for assistance.
  • One light blinks slowly while the other remains continuous. This typically means your heater’s limit switch is malfunctioning. The switch keeps your HVAC system from getting too hot. Reach out to the pros at Air Houston Mechanical LLC for support.

Furnace Blower Runs but No Warmth

Here’s what may be at fault when you hear your heating system’s blower fan running, but you aren’t receiving any heated air.

  • Both lights display alternating quick blinks. This indicates your furnace ignitor might not be in working order. This component lights energy in your heating system to produce warm air and should be repaired by a specialist from Air Houston Mechanical LLC.

Turn to Us for Skilled Furnace Repair

When you need to have your HVAC equipment repaired quickly, turn to the professionals at Air Houston Mechanical LLC. Our techs will fix the problem without delay and have your house feeling comfortable again in a short time. Call us at (832) 501-3419 or contact us online to request an appointment right away.

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