Lennox Furnace Repair Guide | Troubleshooting, Error Codes & More

Not every Lennox furnace repair needs expert intervention. Some issues are DIY, and you only need to know how to diagnose and troubleshoot them accordingly.

As a Canadian homeowner, there is nothing more useful during the cold winter than a Lennox furnace. It keeps your home warm and more comfortable. So, yes, you should worry when your Lennox furnace is not working or malfunctioning.

This guide will help you recognize common Lennox furnace issues and error codes and fix them. You’ll also learn when it’s wise to call a furnace repair expert, given that not all problems are DIY.

Lennox Furnace Repair Guide

Below are everyday Lennox furnace problems and their fixes:

1.     Furnace Not Heating

If your furnace is not heating, the chances are that the fuse or circuit breaker is faulty. If so, then the solution is to replace it. The other possible reason to explain a non-heating furnace is a defective igniter. You need to check for cracks, and if you find any, replace the igniter.

2.     Furnace Cannot Blow Hot Air

A properly working Lennox furnace should blow adequate hot air. If that is not the case, there is a problem with the blower motor that needs addressing. It could be a burned motor or a broken connecting belt. If it’s the first case, you should replace the motor but replace the belt if it’s the second.

3.     Furnace Blowing Excess Air

If the furnace is blowing a lot of air, the problem is often the control board, which regulates the voltage. If the control board is faulty, it will relay the wrong voltage information to the motor, making the furnace blow excess air. This problem, however, is fixable by replacing the control board.

4.     Furnace Keeps Stopping

Usually, a flame sensor monitors the furnace burner and indicates when it goes off. But if the flame is faulty, it won’t do its job well, and thus the furnace will stop. That usually happens when the flame sensor is dirty or just defective. If it’s dirty, you should clean it, but you should replace it if it’s faulty.

5.     Furnace Cycles Irregularly

If your furnace doesn’t circle regularly, it could indicate a problem with the thermostat. The chances are that it’s not well-adjusted, making it difficult for the furnace to cycle correctly. So, check the furnace for an adjustable calibration function and adjust it. If that doesn’t fix the issue, consider replacing the thermostat as it could be faulty.

Lennox Furnace Error Codes and What They Mean

Lennox furnaces usually feature two LEDs which you can look at to identify a problem with the Lennox furnace. So, you have to look keenly at how the two LEDs flash or blink to tell if the furnace is working well or not.

Here are the most typical LED error codes and what they mean

1.     Both LEDs Are Blinking Fast – in Alternating Manner

This problem indicates that your Lennox furnace is not receiving the correct voltage or that the furnace igniter is dysfunctional.

In the first case, you have to check for a loose connection and fix it. Also, avoid using an extension on the furnace if you are using one. In the second case, you should call an expert to help you fix the furnace igniter

2.     Both LEDs Are Blinking Slowly – in Alternating Manner

This issue indicates a flame failure, and it could be because of a faulty HVAC system. This problem is often technical and so don’t fix it. Just call an HVAC expert.

3.     LED 1 Flashing Slowly while LED 2 is Off

The error code indicates there is a flame but no gas detection. It could be because of a problem with the igniter, valve, or gas supply. Don’t fix this problem, however, as it’s too technical. Just call an expert

4.     LED 1 Flashing Slowly while LED 2 Flashes Continuously

This problem indicates an open high-limit switch, and it usually happens to protect the HVAC from overheating.

5.     LED 1 is Off While LED Flashes Slowly

The error code shows that the pressure switch circuit is not open, or the draft inducer is defective. You can open the switch circuit in the first case or replace the inducer in the second to fix the problem.

6.     LED 1 Blinking Fast While LED 2 is Slow

This issue shows reverse furnace polarity, and it could be because of a heated wiring problem. So, don’t try fixing this issue. Just call an expert.

7.     LED 1 Blinking Slowly While LED 2 is Fast

This problem shows a low flame which could be a malfunctioning heat system. Ordinarily, cleaning the flame sensor fixes the issue, but call an expert if the rod is out of place.

8.     Both LEDs Are Off

If both LEDs are off, it shows the furnace is not receiving enough power. So, check the fuse to ensure it’s well set. If not, flip it well, but call an expert if the problem recurs repeatedly.

When to Call A Professional to Repair Your Lennox Furnace

While it’s possible to fix some Lennox furnace repairs, you should leave others to experts. They include:

  • Leakage that’s resulting in some pool of water on the floor
  • Gas smell
  • Dysfunctional heat exchanger
  • The furnace cannot stop blowing in cold air, and it has nothing to do with a thermostat
  • The furnace is not heating at all
  • There is no gas detection
  • The furnace has visible cracks
  • The HVAC system is faulty
  • Sensor rod looks out of place or is faulty

The Question is – Who Do You Call?

Overall, it’s essential to call a certified HVAC or Lennox furnace expert to fix the above issues properly. If you are within Toronto or the Greater Toronto Area (GTA), call Climate Experts.

We are a certified and insured Lennox dealer in Toronto and GTA and their surroundings.  We have the right experts to handle Lennox furnace repair, installations, and sales.

Lennox Warranty Coverage

Every Lennox furnace comes with a warranty cover for its heat exchanger and parts. Note, however, that the coverage depends on the furnace model.

For example, Lennox Merit and Lennox X Elite models come with 5-year coverage for the components and 20-year coverage for the heat exchanger.  Dave Lennox Signature furnaces, in contrast, come with 10-year coverage for the components and 20-year coverage for the heat exchanger.


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