How old is my Lennox unit?

Lennox is part of Lennox International. 2 serial formats sourced across central air conditioner, heat pump, furnace, packaged unit.

• Lennox air conditioner serial numbers in the 1973 to present format encode the year as digits 3-4 (YY) and the month as letter at position 5 (A=Jan .. M=Dec, I skipped) (source: building-center.org).
• Example: serial 5899L17212 decodes to November 1999.
• Lennox air conditioner serial numbers in the before 1972 format encode the year as digits 1-2 and the month as digit(s) 3(-4), 1-12 (source: building-center.org).
• Example: serial 6512 decodes to December 1965.
• Lennox's official lookup at lennox.com returns Your Product's Coverage.

Decoder pages by product

Format eras

• 1973 to present VERIFIED
  ####A#####Central Air Conditioner, Heat Pump, Furnace, Packaged Unit
• before 1972 VERIFIED
  ####Furnace, Central Air Conditioner

Sources

• https://www.building-center.org/lennox/
• https://www.lennox.com/residential/owners/assistance/warranty/official

Lennox central air conditioner Lennox heat pump Lennox furnace Lennox packaged unit Lennox International and Allied Air family Guides