Lennox Furnace Codes Diagnostic – Frequently Asked Questions

Do you have a Lennox furnace with a diagnostic code? If so, you’re not alone. The Lennox diagnostic codes are a common issue with the furnaces. If your furnace has a diagnostic code and isn’t coming on, it is probably due to one of the many reasons listed below. You might also want to check out our blog post: “Lennox Furnace Codes Diagnostic – Frequently Asked Questions.” Each situation will have its solution. However, regardless of which problem you have, there is an answer for it! These diagnostic codes can appear on just about any piece of equipment that uses electricity, including your furnace. If you see these codes on your furnace, don’t panic! It’s fairly common with this brand of equipment. The article will explain what each code means and offer advice for fixing it.

Error Code 10

If your furnace has an error code 10, it means the blower motor is having issues starting. This could be due to a bad motor, control board, or start capacitor. Most likely it is the start capacitor. The capacitor is the device that creates the high voltage needed for the motor to start spinning. If this capacitor is bad, the motor can’t start. This can be caused by several things. It could just be that the furnace is dirty and needs to be cleaned. There could be enough dust buildup on the inside of the motor to block it from starting. It could also be that the motor is just old and needs to be replaced. This can happen after a few years. If you have a furnace that is only a few years old, and the motor is failing, it could indicate that the furnace is being overloaded. This could happen if the ductwork is too small, or if there are too many high-efficiency furnaces on the same circuit.

Error Code 12

If your furnace has an error code 12, it means the furnace has a short in the wiring. The wiring may be touching the furnace case, a different wire, or it could even have something jammed into it. The wiring could also have come loose from the terminals inside the furnace, causing the short. This could also indicate that the furnace control board is bad. The control board is the brain of the furnace. It sends power to the components that operate the furnace. If the board is bad, it could be shorting out, causing the short. If the wiring is loose, you may just need to tighten it. If it is touching something, you’ll want to move it away. If it has something jammed into it, you’ll want to remove it. If it is shorted out, you’ll want to replace the part that is shorted out.

Error Code 19

An error code 19 means that the furnace does not have enough power to start. This could happen for a few reasons. First, you may have too many things on the circuit. The furnace needs a certain amount of amps to power everything. If you have too many things plugged into the same circuit as the furnace, it won’t have enough power to start. Another thing that could cause this is a weak voltage at the circuit. If there is a break in the line or something is wrong with the voltage coming into your home, the furnace won’t have enough power to start. This can also happen if you have too many things plugged into the same circuit.

Error Code 21

Furnaces with an error code 21 are having issues with the gas valve. The gas valve is what opens and closes the gas that fuels the furnace. The valve could be dirty or it could be broken. This can happen after many years of use. If it is dirty, you’ll want to clean it. If it is broken, you’ll want to replace it. The valve could also be jammed. This can happen if something is blocking it from fully closing. This can be caused by lint or dust buildup in the valve. It can also be caused by a clog in the line. If the valve is jammed, the furnace won’t be able to get the gas it needs to operate.

Error Code 22

An error code 22 means that the gas valve is stuck in the open position. This can happen if the valve is broken or if something is blocking it. If the valve is broken, you’ll want to replace it. If it is jammed, you’ll want to clear whatever is blocking it. It could be that lint or other debris has built up around the valve. This could happen if the furnace hasn’t been cleaned regularly. You want to clean the valve regularly to keep it from becoming clogged.

Error Code 23

An error code 23 means that the gas valve is stuck in the closed position. This could happen if the valve is broken or if something is blocking it. If the valve is broken, you’ll want to replace it. If it is jammed, you’ll want to clear whatever is blocking it. It could be that lint or other debris has built up around the valve. This could happen if the furnace hasn’t been cleaned regularly. You want to clean the valve regularly to keep it from becoming clogged.

Error Code 24

An error code 24 means that the gas valve is reversing during operation. This could happen if the wiring to the valve is bad. It could also happen if the valve is broken. If the wiring is bad, you’ll want to replace it. You’ll also want to check the rest of the wiring in the furnace as well. If the wiring is loose or damaged, you may want to replace the entire wiring harness. If the valve is broken, you’ll want to replace it.

Error Code 27

An error code 27 means that the furnace’s flame sensor is bad. The furnace uses this sensor to monitor the flame inside the furnace. If the sensor is bad, the furnace will shut itself off. This can happen if something is blocking the sensor. It could also happen if the sensor is broken. The sensor could be dirty or have lint or other debris around it. If so, you’ll want to clean it. If it is broken, you’ll want to replace it.

Error Code 28

An error code 28 means that the oxygen sensor is bad. The furnace uses this sensor to monitor the amount of oxygen in the exhaust. If the sensor is bad, the furnace will shut itself off. This can happen if something is blocking the sensor. It could also happen if the sensor is broken. The sensor could be dirty or have lint or other debris around it. If so, you’ll want to clean it. If it is broken, you’ll want to replace it.

Summary

Lennox furnaces can be complicated. They also have some codes that may be unfamiliar to some people. We hope that this article helped clear up some of the confusion surrounding Lennox furnace codes. If you have any questions after reading this, please don’t hesitate to reach out! We’d love to help. If your furnace has a diagnostic code and isn’t coming on, it is probably due to one of the many reasons listed above. You might also want to check out our blog post: “Lennox Furnace Codes Diagnostic – Frequently Asked Questions.” Each situation will have its solution. However, regardless of which problem you have, there is an answer for it!