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

December 06, 2019

While your Lennox® furnace can’t chat with you, it has a process to get your attention when there’s a furnace error.

Its control panel has a set of LED lights that can display a fault code. Depending on the fault, your heating system may display continuous or flashing lights.

Though there are a few simple HVAC repairs you can do without an expert, many services are best left to the professionals. When your furnace won’t start or deliver heat, contact B & B Heating & Cooling at 314-325-7552 for professional furnace repair in Florissant.

Our technicians will rapidly spot and repair the problem, even if you don’t have a Lennox furnace. We can service any kinds or makes—and get the heat returned to your home without delay.


What Does the Flickering Light on My Heater Mean?

Your heater uses lights to flash code when it requires repairs. It also works these lights to let you know it’s running properly.

Regular heating consists of:

  • Both lights flash slowly—heater running like it should.
  • Simultaneous fast flash—heater is beginning to call for heat.

If you see a lone light blinking slowly and the other going on and off rapidly, your furnace might be experiencing a low flame signal. This can happen even when your furnace is running correctly. It signifies the flame sensing rod may need to be cleaned or in the wrong spot on the burner. Reach out to us at 314-325-7552 for assistance.

Here are some of the most common issues for Lennox furnaces.

Heater Refuses to Start

Here are a few of the light patterns you may observe when your heat refuses to or keep heating. The majority of these errors must be repaired by a professional, for instance from B & B Heating & Cooling.

  1. All LED lights are off. This means your heating system might not have power. Go to the breaker box to confirm the heater fuse isn’t flipped. Try resetting the fuse if it has moved into the “off” position. If it instantly trips after a subsequent reset, don’t try to reset it again and get in touch with us us at 314-325-7552.
  2. An individual light is stable and the other is flickering slowly. This implies the flame rollout switch is may be open. The switch is an important safety tool that aids in avoiding fires and carbon monoxide. You shouldn’t try to fix this malfunction on your own.
  3. One light is blinking quickly and the other is blinking slowly. This likely signifies power polarity has been reversed. Your furnace could have a wiring issue that requires specialized support from B & B Heating & Cooling.
  4. The pair of lights are flashing slowly. This means your heating system’s blower motor probably isn’t operating. This piece distributes warm air from the heater into your space. We can help in determining what’s causing a problem with this piece.
  5. An individual light is flickering slowly and the other is flickering fast. This means your heating system could have insufficient voltage or a short circuit. Call our technicians at 314-325-7552 for help.
  6. One light is flashing on, on and off while the other flashes on, off, on. This indicates there may be a fault with your heating system’s control panel or wiring. B & B Heating & Cooling can find the error and fix it.
  7. The pair of lights display every other slow blinks. This indicates your heater may have a flame error. There could be trouble with its gas supply, gas valve or ignitor control. Call us at 314-325-7552 for support.
  8. One light flickers slowly while the other stays continuous. This often indicates your HVAC equipment’s limit switch is not working. The switch stops your heater from overheating. Reach out to the experts at B & B Heating & Cooling for support.

Heater Blower Operates But No Heat

Here’s what might be at fault when you hear your heater’s blower fan working, but you aren’t receiving any warmth.

  • The duo of lights are giving every other quick blinks. This indicates your furnace ignitor could not be working. This part lights energy in your furnace to create warm air and should be serviced by a professional from B & B Heating & Cooling.

Depend on Us for Skilled Furnace Repair

When you need to get your heating system in working order quickly, turn to the technicians at B & B Heating & Cooling. Our pros will fix the problem quickly and have your space feeling relaxing again in no time. Get in touch with us at 314-325-7552 or contact us online to request an appointment today.