Lennox serial age
Manufacture date from the rating-plate serial. Same family as Armstrong Air, Ducane, AirEase. A printed MFR date on the plate still wins.
Lennox
Type the serial off the rating plate. Spaces and hyphens are ignored. Manufacture date is not the install date.
Diagnose this call
Age is open. The walkthrough is the seat.
Where the plate is
Many Lennox cabinets also have a separate year sticker. Use that when the serial is ugly. Rating plate is on the blower door or outdoor corner.
Styles
1973–present
1606B13871
Ten characters. First two = plant (not week). Positions 3–4 = year. Fifth character A–L = month. 1606B… = February 2006, plant 16. Do not read this as a Carrier week/year plate.
Before 1973
724
Three or four digits: year then month.
Cross-checked against Lennox HVAC age. FieldBench does not host or republish that page. Letter charts we could not verify are linked out instead of invented.