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

December 06, 2019

While your Lennox® heating system cannot speak to you, it does have a process to get your attention when there’s a furnace error.

Its control panel has a set of LED lights that can share a fault code. Based on the problem, your furnace might display continuous or flashing lights.

Although there are various basic heating repairs you can do on your own, many repairs are best taken care of by experts. When your heater won’t kick on or provide heat, reach out to Contra Costa Heating & AC at 510-343-9841 for skilled furnace repair in the Bay Area.

Our specialists will speedily pinpoint and handle the malfunction, even if you don’t have a Lennox heater. We can fix whichever brands or models—and get the heat reintroduced to your residence fast.


What Does the Blinking Light on My Furnace Mean?

Your heater uses lights to flash code when it needs to be repaired. It also uses these lights to tell you it’s operating properly.

Normal function consists of:

  • Concurrent slow flash—furnace heating correctly.
  • Both lights flash fast—heating system is beginning to call for heat.

If you see a lone light flashing slowly and the other blinking rapidly, your heating system might have a low flame signal. This can happen even when your furnace is running like it should. It indicates the flame sensing rod may need to be cleaned or in the wrong location on the burner. Call us at 510-343-9841 for help.

Here are a few other of the most routine errors for Lennox furnaces.

Heating System Won’t Turn On

Here are many of the light patterns you may observe when your heat won’t turn on or keep operating. The majority of these issues need to be fixed by an expert, such as one from Contra Costa Heating & AC.

  1. All LED lights are off. This means your furnace might not have power. Examine the breaker box to ensure the heater fuse has not flipped. You should reset the fuse if it is in the “off” area. If it instantly trips following a reset, leave the breaker alone and call us at 510-343-9841.
  2. An individual light is solid and the other is blinking slowly. This shows the flame rollout switch is may be not working right. The part is an important safety guard that assists in preventing fires and carbon monoxide. You shouldn’t seek to repair this problem without professional help.
  3. One light is blinking quickly and the other is flashing slowly. This likely means power polarity has been transposed. Your heater may have a wiring problem that needs professional assistance from Contra Costa Heating & AC.
  4. The duo of lights are flickering slowly. This indicates your furnace’s blower motor likely isn’t working. This part distributes heated air from the heating system into your residence. We can help in figuring out what’s causing an issue with this component.
  5. One light is flickering slowly and the other is blinking fast. This means your heating system could have insufficient voltage or a short circuit. Reach out to our experts at 510-343-9841 for help.
  6. One light is flickering on, on and off while the other blinks on, off, on. This signifies there may be a problem with your furnace’s control panel or wiring. Contra Costa Heating & AC can determine the issue and take care of it.
  7. The pair of lights are using alternating slow flashes. This indicates your HVAC system may have a flame problem. There may be trouble with its gas supply, gas valve or ignitor control. Get in touch with us at 510-343-9841 for assistance.
  8. An individual light flashes slowly while the other is continuous. This usually indicates your HVAC system’s limit switch is experiencing an error. The switch prevents your HVAC system from getting too hot. Contact the pros at Contra Costa Heating & AC for assistance.

Furnace Blower Works But No Heat

Here’s what could be broken when you observe your heater’s blower fan working, but you aren’t receiving any warm air.

  • Both lights display alternating quick blinks. This signifies your furnace ignitor may be broken. This piece ignites fuel in your heater to produce heat and should be fixed by a professional from Contra Costa Heating & AC.

Trust Us for Professional Furnace Repair

When you have to get your furnace in working order without delay, trust the technicians at Contra Costa Heating & AC. Our pros will fix the error quickly and have your house feeling comfortable again in a short time. Reach out to us at 510-343-9841 or contact us online to request an appointment right away.