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

December 06, 2019

While your Lennox® furnace can’t speak to you, it possesses a way to communicate a furnace error.

Its control board has double LED lights that can share a fault code. Subject to the malfunction, your heater might display continuous or flashing lights.

Though there are some simple furnace fixes you can do on your own, the majority of fixes are best left to experts. When your furnace won’t kick on or provide warm air, contact Fleming Heating & Air Conditioning Inc at 877-389-2465 for professional furnace repair in South Beloit and Belvidere.

Our experts will quickly pinpoint and take care of the malfunction, even if you don’t use a Lennox furnace. We can service whichever types or configuration—and get the heat returned to your home without delay.


What Does the Blinking Light on My Heater Mean?

Your heater depends on lights to flash code when it isn’t working right. It also works this setup to let you know it’s heating correctly.

Normal function includes:

  • Simultaneous slow flash—furnace working properly.
  • Concurrent fast flash—heater is starting to call for heat.

If you notice a single light blinking slowly and the other blinking quickly, your furnace may be experiencing a low flame signal. This can occur even when your heater is operating properly. It signifies the flame sensing rod might have build-up or in the incorrect spot on the burner. Call us at 877-389-2465 for assistance.

Here are several other of the most common errors for Lennox heating systems.

Heating System Will Not Turn On

Here are some of the light patterns you may observe when your heating system will not or keep heating. Most of these problems need to be repaired by a specialist, for instance from Fleming Heating & Air Conditioning Inc.

  1. Both LED lights are extinguished. This means your heating system might not have electricity. Examine the breaker box to make sure the furnace fuse isn’t tripped. Attempt to reset the fuse if it is in the “off” area. If it rapidly turns off following a reset, don’t try to reset it again and contact us at 877-389-2465.
  2. One light is solid and the other is blinking slowly. This shows the flame rollout switch is may be open. The switch is an essential safety device that aids in stopping fires and carbon monoxide. You shouldn’t try to handle this issue yourself.
  3. One light is flickering fast and the other is blinking slowly. This typically means power polarity has been transposed. Your furnace may have a wiring error that requires specialized assistance from Fleming Heating & Air Conditioning Inc.
  4. Both lights are flickering slowly. This indicates your heater’s blower motor probably isn’t operating. This piece distributes warm air from the heater into your rooms. We can help in determining what’s causing a problem with this piece.
  5. A single light is blinking slowly and the other is flashing quickly. This means your HVAC system could have insufficient voltage or a short circuit. Get in touch with our professionals at 877-389-2465 for support.
  6. One light is flickering on, on and off while the other flashes on, off, on. This means there could be trouble with your HVAC system’s control panel or wiring. Fleming Heating & Air Conditioning Inc can pinpoint the error and fix it.
  7. Both lights are using alternating slow flashes. This indicates your heater may have a flame error. There might be a problem with its gas supply, gas valve or ignitor control. Get in touch with us at 877-389-2465 for help.
  8. A single light flickers slowly while the other remains steady. This usually indicates your furnace’s limit switch is not working. The switch keeps your heater from getting too hot. Get in touch with the specialists at Fleming Heating & Air Conditioning Inc for support.

Heating System Blower Works But No Heat

Here’s what could be wrong when you hear your furnace’s blower fan running, but you aren’t getting any warm air.

  • The duo of lights display every other quick flashes. This means your furnace ignitor could be broken. This part lights gas in your heating system to make heat and should be fixed by a specialist from Fleming Heating & Air Conditioning Inc.

Turn to Us for Expert Furnace Repair

When you need to get your HVAC equipment in working order fast, depend on the experts at Fleming Heating & Air Conditioning Inc. Our technicians will handle the issue quickly and have your house feeling comfortable again in a short time. Reach out to us at 877-389-2465 or contact us online to schedule an appointment today.