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

December 06, 2019

While your Lennox® furnace can’t speak to you, it does have a procedure to tell you about a furnace error.

Its control panel has a set of LED lights that can display a fault code. Subject to the malfunction, your heater could display continuous or flashing lights.

Though there are some elementary HVAC repairs you can finish without an expert, the majority of services are best handled by experts. When your heater won’t start or deliver warmth, get in touch with O'Brien Heating & Air Conditioning at 610-257-7035 for expert furnace repair in Drexel Hill.

Our technicians will quickly identify and handle the malfunction, even if you don’t own a Lennox heater. We can repair whichever kinds or makes—and get the warmth reintroduced to your house quickly.


What Does the Flashing Light on My Heating System Mean?

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

Correct operation involves:

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

If you see one light going on and off slowly and the other flashing quickly, your heating system may be having a low flame signal. This can happen even when your heating system is working properly. It means the flame sensing rod may be dirty or in the incorrect spot on the burner. Call us at 610-257-7035 for help.

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

Heater Will Not Kick On

Here are many of the light sequences you might notice when your heating system will not or keep operating. The bulk of these problems need to be fixed by a professional, such as one from O'Brien Heating & Air Conditioning.

  1. Both LED lights are off. This indicates your furnace might not have power. Go to the breaker box to ensure the heater fuse has not triggered. Try resetting the fuse if it has moved into the “off” area. If it instantly trips following a reset, leave the breaker alone and contact us at 610-257-7035.
  2. A single light is stable and the other is blinking slowly. This implies the flame rollout switch is possibly open. The component is an important safety device that helps in preventing fires and carbon monoxide. You shouldn’t seek to fix this fault yourself.
  3. An individual light is blinking quickly and the other is flickering slowly. This typically indicates power polarity has been reversed. Your heater might have a wiring problem that calls for specialized help from O'Brien Heating & Air Conditioning.
  4. All lights are blinking slowly. This signifies your heater’s blower motor possibly isn’t operating. This component moves heated air from the HVAC system into your space. We can aid in figuring out what’s causing a problem with this component.
  5. An individual light is flickering slowly and the other is blinking quickly. This indicates your furnace could have not enough voltage or a short circuit. Contact our professionals at 610-257-7035 for assistance.
  6. One light is flashing on, on and off while the other blinks on, off, on. This signifies there may be an error with your heater’s motherboard or wiring. O'Brien Heating & Air Conditioning can determine the problem and handle it.
  7. The pair of lights show alternate slow flickers. This signifies your heating system may have a flame problem. There might be an issue with its gas supply, gas valve or ignitor control. Contact us at 610-257-7035 for help.
  8. One light flashes slowly while the other stays solid. This often indicates your HVAC equipment’s limit switch is open. The switch keeps your HVAC system from overheating. Contact the specialists at O'Brien Heating & Air Conditioning for assistance.

Furnace Blower Runs But No Warmth

Here’s what may be broken when you notice your heater’s blower fan working, but you aren’t gaining any heat.

  • Both lights display alternating fast flashes. This signifies your furnace ignitor may not be in working order. This part kindles energy in your HVAC equipment to create warm air and should be repaired by a technician from O'Brien Heating & Air Conditioning.

Depend on Us for Expert Furnace Repair

When you have to get your heater in working order fast, depend on the professionals at O'Brien Heating & Air Conditioning. Our technicians will fix the error quickly and have your space feeling comfortable again in no time. Contact us at 610-257-7035 or contact us online to schedule an appointment now.