Lennox® HVAC Age Checker

    Enter your Lennox serial number below to determine the manufacturing year of your HVAC system

    The serial number is usually found on a label on your HVAC unit

    Add model number for AI-powered specs including tonnage, SEER rating, and features

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    How to Find Your Serial Number

    Your Lennox serial number can typically be found on:

    • The rating plate on your outdoor condensing unit
    • Inside the furnace cabinet door
    • On the unit's warranty documentation

    Lennox Serial Number Formats

    Style 1 (1973-Present)

    Example: 1606B13871 or 5899L17212

    First 2 digits: Factory Code | Positions 3-4: Year | Position 5: Month (letter)

    Style 2 (Prior to 1973)

    Example: 724 or 6512

    Positions 1-2: Year | Position 3 or 3-4: Month (numeric)