Furnace troubleshooting

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

While your Lennox® furnace isn’t able to speak to you, it has a way to get your attention when there’s a furnace error.

Its motherboard has a set of LED lights that can display a fault code. Based on the fault, your furnace may show solid or flashing lights.

Although there are certain elementary furnace repairs you can do without an expert, most tasks are best taken care of by experts. When your heater refuses to kick on or put out warm air, call Controlled Comfort HVAC Inc at 224-412-8308 for experienced furnace repair in Carpentersville.

Our experts will swiftly discover and repair the problem, even if you don’t have a Lennox furnace. We can service all brands or configuration—and get the heat restored to your home quickly.


What Does the Blinking Light on My Furnace Mean?

Your furnace relies on lights to flash code when it needs to be repaired. It also engages this setup to tell you it’s working like it should.

Regular heating includes:

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

If you realize that one light going on and off slowly and the other flashing rapidly, your heating system might be experiencing a low flame signal. This can happen even when your heating system is running correctly. It indicates the flame sensing rod could be dirty or in the incorrect location on the burner. Call us at 224-412-8308 for support.

Here are a few other of the most typical errors for Lennox HVAC systems.

Furnace Refuses to Kick On

Here are many of the light patterns you might notice when your heat won’t turn on or keep heating. The bulk of these errors need to be taken care of by a specialist, for instance from Controlled Comfort HVAC Inc.

  1. Both LED lights aren’t lit. This means your heater might not have electricity. Find the breaker box to make sure the furnace fuse isn’t triggered. Try resetting the fuse if it has moved into the “off” position. If it rapidly flips after a subsequent reset, leave the breaker alone and call us at 224-412-8308.
  2. A single light is continuous and the other is blinking slowly. This means the flame rollout switch is likely malfunctioning. The component is a critical safety tool that aids in avoiding fires and carbon monoxide. You shouldn’t seek to handle this issue yourself.
  3. One light is flashing rapidly and the other is flashing slowly. This likely indicates power polarity has been inverted. Your heating system might have a wiring error that calls for professional assistance from Controlled Comfort HVAC Inc.
  4. Both lights are flickering slowly. This means your furnace’s blower motor likely isn’t operating. This component circulates heated air from the heater into your rooms. We can assist in pinpointing what’s wrong with this component.
  5. An individual light is blinking slowly and the other is flickering rapidly. This means your heating system could have not enough voltage or a short circuit. Call our technicians at 224-412-8308 for support.
  6. One light is flickering on, on and off while the other flashes on, off, on. This indicates there might be trouble with your HVAC system’s motherboard or wiring. Controlled Comfort HVAC Inc can pinpoint the issue and fix it.
  7. The duo of lights are using every other slow blinks. This means your HVAC system likely has a flame problem. There may be an issue with its gas supply, gas valve or ignitor control. Reach out to us at 224-412-8308 for support.
  8. An individual light flashes slowly while the other stays continuous. This typically signifies your furnace’s limit switch is open. The switch stops your heater from overheating. Call the specialists at Controlled Comfort HVAC Inc for help.

Heating System Blower Works But No Warmth

Here’s what may be broken when you observe your heater’s blower fan running, but you aren’t getting any heat.

  • The pair of lights are giving alternating rapid blinks. This signifies your furnace ignitor might not be in working order. This component ignites energy in your furnace to make warmth and should be fixed by a specialist from Controlled Comfort HVAC Inc.

Turn to Us for Skilled Furnace Repair

When you need to have your heating system in working order without delay, turn to the professionals at Controlled Comfort HVAC Inc. Our technicians will handle the fault promptly and have your space feeling relaxing again soon. Reach out to us at 224-412-8308 or contact us online to schedule an appointment now.

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