Month of manufacture is in the 5th character.Year of manufacture is in the 3rd-4th character.#5120L13681 (Ten (10) character Serial number begins with four (4) numerical digits followed by one (1) letter and ends with five (5) numerical digits.) Lennox have a different styles of serial number. The date of the manufacture or age of Lennox® HVAC unit can be determined from the serial number located on the data plate. The first 2 numbers stand for the factory location, the second 2 numbers are the year and the following letter is the month.

New Lennox serial numbers usually contain 4 numbers followed by a letter. Now that you know the location of Lennox serial number, its time to decode it. Find a metal nameplate attached in the backside of the cabinet. Lennox serial number of AC and Heat Pump unit can be found on the side of the air conditioner housing of the outdoor unit. Serial Number Location on Lennox AC and Heat Pump Find the series of numbers and letter that follow the word “Serial” on that data plate. Looking to the left side of the in house cabinet or the top of the blower deck. You can find the Lennox serial numbers and model numbers of your furnace by removing the top-front support panel. The sticker is actually attached to the circuit board inside. The Lennox serial number should be on a little sticker that is attached on the back of the unit inside the main case. If your unit is getting close to that age range, you may want to consider to replace. Lennox HVAC units have a beneficial life up-to 20 years in general. When deciding whether to repair or replace your HVAC unit, it’s a good idea to check out the age of the unit first. But first, you must find the location and be able to read and decode the Lennox nomenclature. You can identify the Lennox furnace age by serial number. Serial number is important to identify the age of the unit.

Read on to know more about Lennox serial number, where to find and how to decode it. Serial number indicating the age of the unit and where it was manufactured. Lennox serial number is attached on the data plate that provides essential information regarding the unit.

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