Lennox Furnace Repair Guide
What’s Wrong With Your Lennox Furnace?
| Is your furnace... | The problem might be your... | What's wrong? | How you can fix it: |
|---|---|---|---|
| Not heating? | Circuit Breaker/Fuse | Most likely, either the electrical system providing your furnace’s power has shorted or the power switch has blown. | Try resetting your furnace’s circuit breaker. If it has blown, you will need to replace it. |
| Igniter | The furnace’s igniter might either be cracked or faulty. | Check the part for cracks, if it is then replace the igniter. If it isn’t cracked, use a multimeter to test for continuity. | |
| Cycling irregularly? | Thermostat | Your thermostat might be adjusting incorrectly, causing the furnace to cycle on and off too often. | If your thermostat has an adjustable calibration scale, adjust the heat anticipator. If this does not stabilize the unit, you may have to replace the thermostat. |
| Not blowing hot air? | Blower Motor | Your blower motor may have completely burnt out. If this doesn’t seem to be the case, then the connecting belt may have simply broken. | Test to see if power is reaching the motor. If it does, but isn’t running, the motor has likely failed. If the motor runs but air doesn’t move, the connecting belt has probably broken. You’ll have to replace the belt. |
| Blowing too much air? | Control Board | The control board regulates the amount of voltage that reaches each functioning part. If the relay that controls the blower motor has failed, it will continually send voltage to the motor. | Replace the control board. |
| Thermostat | The contact that controls the blower motor on your thermostat may be stuck closed, causing the blower motor to run continuously. | Use a multimeter to check for continuity. If it appears the thermostat is the issue, replace it. | |
| Leaking water? | Drain Pipe | ||
| Starting and then stopping shortly after? | Flame Sensor | Your furnace’s flame sensor monitors the burner, detecting whether a flame is present. If it is either defective or dirty, it will not be able to detect a flame. | If dirty, clean the sensor using a fine abrasive pad. If faulty, replace the flame sensor. |
How to Replace Your Air Filter
- Check your owner’s manual to find out what kind of replacement filter you need for your particular Lennox furnace model.
- When you have the new filter, remove the access panel from the furnace (or slide it open) to get to the filter.
- Slide out the old filter.
- Find the arrows on the new filter and use them as a guide for inserting it, and then slide it into place.
- Close or replace the access panel.
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Lennox Furnace Error Codes
| Lennox Error Code | What this means | How to fix it |
|---|---|---|
| The pair of LED lights are extinguished. | This means your HVAC system might not be receiving power. | Find the breaker box to make sure the furnace fuse isn’t flipped. Try resetting the fuse if it’s in the “off” spot. If it promptly trips following a reset, don’t try to reset it again and get in touch with your local HVAC service provider. |
| A single light is continuous and the other is flickering slowly. | This shows the flame rollout switch is possibly not working right. The component is a critical safety device that aids in preventing fires and carbon monoxide. | You shouldn’t seek to fix this problem yourself. Contact your local HVAC service provider. |
| One light is blinking fast and the other is flickering slowly. | This often signifies power polarity has been reversed. | Your heating system may have a wiring issue that needs specialized help from your local HVAC service provider. |
| All lights are flickering slowly. | This indicates your furnace’s blower motor possibly isn’t operating. This piece circulates heated air from the HVAC system into your residence. | Contact your local HVAC service provider. |
| An individual light is flashing slowly and the other is flashing fast. | This signifies your HVAC system might have low voltage or a short circuit. | Contact your local HVAC service provider. |
| One light is flickering on, on, off while the other flashes on, off, on. | This means there could be trouble with your heater’s control panel or wiring. | Contact your local HVAC service provider. |
| The duo of lights display alternate slow flickers. | This indicates your HVAC system may have a flame error. There might be a problem with its gas supply, gas valve or ignitor control. | Contact your local HVAC service provider. |
| A single light flickers slowly while the other stays solid. | This usually means your HVAC system’s limit switch is not working. The switch stops your HVAC system from getting too hot. | Contact your local HVAC service provider. |
When to call a professional to repair your Lennox furnace
- Is making noises, including squealing, rattling, and whistling, which are often caused by a mechanical problem
- Has cracks in it
- Is leaking or has water pooling on the floor around it
- Isn’t blowing hot air or isn’t producing any heat
- Is emitting a gas odour
- Has a problem with the heat exchanger
- Is blowing cold air and the thermostat isn’t the cause
- Won’t stay on because the flame sensor needs to be replaced
Who Should You Call?
Lennox’s Warranty Coverage
- Dave Lennox Signature Collection series: Furnaces in this series have a 10-year warranty on covered components and a 20-year warranty on the heat exchanger.
- Elite series and Lennox Merit series: These models have a five-year warranty on covered components and a 20-year heat exchanger warranty.
Lennox Furnace Model Numbers
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