How old is my Lennox? How can I tell using the serial number?
Answer: For most Lennox equipment, the third and fourth characters of the serial number are numbers, and they indicate the year. For example, 94 is 1994 and 08 is 2008.
The fifth character is a letter that corresponds to a month – A is January, for example. The month key code is found below.
How to Read a Lennox Serial Number
This Lennox serial number lookup works for the Lennox age of unit lookup on air conditioners, heat pumps, gas furnaces, air handlers, boilers and mini split ductless heat pumps.
In total, Lennox has used 4 different styles of serial numbers on their furnaces, boilers, heat pumps, air handlers, AC units, and mini-splits.
These serial numbers date back to the 1960’s but the current style has been used since 1974 on all Lennox HVAC equipment making serial number lookup and easy task.
These aren’t model numbers: This post is about Lennox serial numbers, not Lennox model numbers that have nomenclature related to series, capacity, and performance of Lennox HVAC equipment.
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Where is the Lennox Serial Number?
You can find the serial number on the rating or data plate, sometimes called a rating or data tag.
On a Lennox furnace, you will find the rating plate by removing the top, front, service panel. The rating plate is often placed on the left side of the cabinet, although the type of furnace you have may impact the exact placement.
On a Lennox boiler you can find the rating plate on the exterior at the top of the unit.
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On Lennox air conditioners, heat pumps and mini-splits, look for the rating plate on the exterior of the unit near the service panel.
These information tags are hard to miss. They contain the serial number, which might be written “Serial #” or “S/N,” and they contain other specs like voltage. The model number is on the tag too.
How to Read a Lennox Serial Number – Details
In each of these examples, the characters that indicate the manufacture date have been underlined. The other numbers and letters identify the plant where the unit was made and the sequence of manufacture.
Style #1: 10 Characters – Numbers and One Letter – 1974 to Present
Style # 1 is the most common style and always begins with 4 numbers, followed by one letter, and ends with 5 more numbers.
The first 2 numbers usually indicate the factory where the unit was made and are not used in decoding the manufacture date.
Example serial number: 5205J24862
Year: the 3rd and 4th numbers indicate the manufacture year, here 05, so the year is 2005.
Month: The 5th character, which is a letter, indicates the month the unit was made based on the Lennox Month of Manufacture code below. In this case the letter is J so the unit was made in September.
Manufacture Date: September 2004
This image shows this serial number type.
The unit was produced in August 2019.
Style # 2: 9 Characters – Letters & Numbers – Late 1970s to Early 1990s
Style # 2 begins with a letter, followed by 5 numbers, and ends with 3 letters. This style was primarily used in the late 1970s through the early 1990s.
Example Serial #: C86185EDC
Year: The 2nd and 3rd characters are numbers and indicate the year the unit was made. These numbers are 86, so the unit was made in 1986.
Month: The second to last character is a letter indicating the month of manufacture, here the letter is “D”, so the unit was made in April. See the Lennox Month of Manufacture code below.
Manufacture Date: April 1986
Style #3: 10 Characters – Numbers and Letters – 1960s and 1970s
Style # 3 begins with 2 numbers, then a letter, then 2 more numbers, followed by 2 more letters, and three more numbers. This style was in the 1960’s and 1970’s.
Example Serial #: 09B56JK590
Day: The 1st and 2nd characters represent the day of the month the unit was made. In this case the numbers are 09, so the 9th day of the month.
Month: The 3rd character is a letter and indicates the month the unit was made. The letter is a “B”, so the unit was made in February, based on the Lennox Month of Manufacture code below.
Year: The 4th and 5th characters indicate the year, in reverse, that the unit was made. These numbers in the example are “56”, so the unit was made in 1965.
Manufacture Date: February 9, 1965
Lennox Code for Month of Manufacture
A = January G = July
B = February H = August
C = March J = September
D = April K = October
E = May L = November
F = June M = December
Note that the letter “I” is not used – probably because it could be confused with the number 1.
Style # 4: 10 Characters – All Numbers
Style # 4 uses all numbers. The 7th and 8th numbers indicate the year that the unit was made and the 9th and 10th numbers represent the week of the year the unit was made.
Example Serial #: 4592711225
Year: The 7th and 8th numbers are 12, so the year is 2012
Month: The 9th and 10th numbers are 25, so the 25th week of the year will fall in June.
Manufacture Date: June 2012
Common Issues with Older Lennox Units
As Lennox HVAC systems age, they may begin to experience performance declines or require more frequent maintenance. While these units are built to last, wear and tear over time can lead to a few common issues. Identifying these problems early can help you decide whether to repair or replace your system.
1. Declining Energy Efficiency
One of the most noticeable issues with older Lennox units is declining energy efficiency. Units over 15 years old typically have lower SEER (Seasonal Energy Efficiency Ratio) ratings compared to modern systems. As a result, they consume more energy to produce the same level of heating or cooling, leading to higher utility bills.
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Older units may also struggle to maintain consistent temperatures, which can cause the system to cycle on and off more frequently, further increasing energy consumption.
2. Frequent Breakdowns and Repairs
As components wear out, older Lennox systems are more prone to frequent breakdowns. Common repair needs include:
- Compressor failures: A worn compressor may struggle to regulate refrigerant flow, reducing the unit’s ability to cool effectively.
- Coil leaks: Over time, evaporator and condenser coils can corrode, causing refrigerant leaks that impair performance.
- Fan motor issues: Fans may begin to fail, leading to reduced airflow and uneven heating or cooling.
If repair costs are adding up, it might be more economical to replace the unit with a newer, more efficient system.
3. Outdated Refrigerants
Older Lennox units may still use R-22 refrigerant, which was phased out in 2020 due to environmental regulations. R-22 is no longer produced, and supplies are limited, making it costly to recharge systems that rely on this refrigerant.
Modern units use R-410A refrigerant, which is more energy-efficient and environmentally friendly. If your system still uses R-22, upgrading to a new unit can help you avoid the high costs of maintenance and ensure compliance with current standards.
4. Increased Noise Levels
Older HVAC systems often become noisier over time. This could be due to:
- Worn bearings in the fan motor.
- Loose or damaged components like panels and ducts.
- Aging compressors that create a loud humming or grinding noise.
While some noise issues can be repaired, persistent or worsening noise may indicate that the system is nearing the end of its useful life.
5. Uneven Heating or Cooling
Another issue common in older Lennox units is uneven heating or cooling throughout your home. This problem may result from:
- Weak airflow caused by a failing blower motor or dirty ductwork.
- An inability to maintain consistent temperatures due to worn components.
- Refrigerant leaks affecting the unit’s cooling capacity.
If certain rooms feel too warm or too cold while others remain comfortable, it’s time to evaluate the system’s efficiency and consider an upgrade.
By keeping an eye out for these common issues, you can better assess the condition of your Lennox HVAC system and decide whether repairs or a replacement would be the more cost-effective option. Regular maintenance can help extend the life of your system, but when problems become frequent or costly, upgrading to a modern, energy-efficient Lennox unit may provide better comfort and long-term savings.
Interested in Replacing Your Lennox HVAC Unit?
You can check the latest Lennox HVAC systems cost here and we update the prices yearly. Or you can use our free quote tool to get 3 estimates in a minute, which already takes rebates and tax credit into consideration and filter the unqualified contractors automatically.
Maintenance Tips for Extending the Life of Your Lennox HVAC Unit
Maintaining your Lennox HVAC unit properly can significantly extend its lifespan and ensure it runs efficiently. Regular maintenance not only prevents unexpected breakdowns but also keeps your energy bills low. Here are essential tips to keep your Lennox unit in top shape:
- Filter Replacement: Change your air filters every 90 days to prevent airflow restriction and maintain air quality. During high usage months, consider checking filters monthly and replace if they appear clogged or dirty.
- Coil Cleaning: The evaporator and condenser coils can accumulate dirt over time, reducing the system’s efficiency. Annually cleaning these coils can enhance your unit’s performance.
- Seasonal Inspections: Schedule professional inspections before the heating and cooling seasons. These check-ups can catch issues early, preventing costly repairs down the line.
- Clear Debris: Keep the area around your outdoor unit clear of leaves, pollen, and twigs. A 2-foot clearance around the unit ensures optimal airflow and reduces the strain on your system.
- Thermostat Settings: Optimize your thermostat settings according to the season. A programmable thermostat can make efficiency adjustments easier, saving energy while maintaining comfort.
By following these maintenance tips, you can extend the lifespan of your Lennox HVAC unit, ensuring it provides comfortable temperatures year-round.
How to Get the Best HVAC Prices
- Firstly, keep in mind that installation quality is always the most important thing for residential HVAC project. So never sacrifice contractor quality for a lower price.
- Secondly, remember to look up the latest rebates as we talked above.
- Thirdly, ask for at least 3 bids before you make the decision. You can click here to get 3 free estimates from your local contractors, and this estimate already takes rebates and tax credit into consideration and filter unqualified contractors automatically.
Lastly, once you chose the right contractor, remember to use the tactics from this guide: Homeowners Tactics When Negotiating with HVAC Dealer to get the final best price.
my Lennex ID # is GF3-110M Y.
before 1970