HVAC Serial Number Lookup
Lennox Serial Number Lookup: AC and Furnace Age
Lennox has its own serial number formats; the rows below say which are read from the manufacturer's own document. Enter the serial from the data plate below to get the manufacture date with a character-by-character explanation, the unit's age, its refrigerant era, and the warranty picture.
Starting the decoder. The serial formats, the refrigerant timeline and the warranty terms further down this page are already loaded, so you can read yours off them now.
7 of the 41 decode rules rest on a single secondary reference. Where two agree, that is weaker evidence than it looks: secondary references copy one another, and agreement between two is not a manufacturer document being read. Some of the formats on this page are read from the manufacturer's own document; the others rest on secondary references, and each row below says which. A date stamped or printed on the data plate always outranks a serial decode.
Lennox furnace not heating?
Its stop checks come first, then what its light or code means, on furnace codes for Lennox. Type what the furnace shows and it opens there with the brand filled in.
Lennox Serial Number Formats
| Format | Era | Example | Confidence |
|---|---|---|---|
| 4 digits + letter + 5 or 6 digits; digits 1-2 = plant, digits 3-4 = year, the letter = month (A-M, skipping I)Cross-checked across 3 secondary references, alongside 2 manufacturer documents held. | 1973/74 to present | 1606B13871 = February 2006, plant 16 | high |
| Letter + 5 digits + 3 letters; digits 2-3 = year, second-to-last letter = monthA single secondary reference, not a manufacturer document. Single source. | late 1970s to early 1990s | C86185EDC = April 1986 | low |
| 10 digits; digits 7-8 = year, digits 9-10 = weekA single secondary reference, not a manufacturer document. Single source. | some 2010s units | 4592711225 = week 25 of 2012 | low |
Some older or conflicting Lennox formats are recognized but deliberately not decoded; the decoder explains why when it sees one instead of guessing.
Worked Example: Lennox 1606B13871
Expected decode: February 2006, plant 16. Character by character:
16 = plant/factory code (digits 1-2)
06 = year 2006 (digits 3-4)
B = February (month letters A to M, skipping I)
13871 = production sequence
Lennox Refrigerant Timeline
| Manufacture year | Typical refrigerant | Notes |
|---|---|---|
| through 1995 | R-22 | R-22 was the standard refrigerant for equipment of this age. R-410A did not become an EPA-accepted substitute for HCFC-22 in household and light commercial air conditioning until February 8, 1996, so a unit built before then predates it. Standard refrigerant of the era. EPA ended U.S. production and import of R-22 on January 1, 2020; an existing system can still be serviced with recycled, reclaimed or previously produced R-22. |
| 1996 to 2009 | R-22 (R-410A on select premium series) | R-22 standard before 2010; R-410A appeared on select premium Lennox series from the mid-2000s. Check the spec sheet in that window. |
| 2010 to 2024 | R-410A | From January 1, 2010, EPA allowed new R-22 to be produced or imported only for use in equipment manufactured before that date; R-410A was the standard through 2024. |
| 2025 and later | R-454B ducted / R-32 ductless | From January 2025 Lennox uses R-454B for whole-home ducted equipment (Merit, Elite, Dave Lennox Signature) and R-32 for its ductless mini splits, one of the few brands split across both A2Ls. |
The refrigerant printed on the nameplate is authoritative; this timeline tells you what is typical for the age, not what is in a specific unit.
Lennox Warranty Terms
Lennox warranty lookup
The maker's own page: Lennox's own warranty lookup, at www.lennox.com. The page is headed "Lennox Warranty Lookup". This page reads no maker's records and cannot show whether a unit was registered. Open Lennox's own warranty lookup
Enter the serial in the lookup on this page for the build date and the unit's age. No Lennox warranty certificate is held here for a dated term, so the result dates no term, says so, and names what would answer it; a Service Brief carries what is known to whoever works on the unit.
One U.S. Consumer Product Safety Commission recall notice this tool matches names Lennox equipment. Where the serial and model entered meet, or may meet, a notice's printed conditions, the result shows that notice first, with CPSC's own hazard and remedy, and compares each condition; where a notice lists models and none was entered, it asks for the model, unless something else entered or read from the serial rules the unit out of that notice. It never says a unit is or is not recalled, and it says nothing when nothing entered meets or may meet one.
What this tool holds on Lennox's warranty
This tool holds Lennox's warranty page but not its certificates. The page links separate certificates for each series, split between units installed before and after February 8, 2022, so the terms for a unit are on the certificate for its series and install date.
The result does not work out a dated term for Lennox: no Lennox certificate is registered for that here. Only the maker's records show whether a unit was registered.
Source: lennox.com warranty page (links the series certificates).
Frequently Asked Questions
How old is my Lennox unit?
Decode the serial number from the data plate. The dominant Lennox format (1973/74 to present) is: 4 digits + letter + 5 or 6 digits; digits 1-2 = plant, digits 3-4 = year, the letter = month (A-M, skipping I). Example: 1606B13871 decodes to February 2006, plant 16. Subtract the decoded year from the current year for the age.
Has the Lennox serial decode been checked against serials somebody else dated?
Lennox plant + year + month letter: Read against 5 serials where a public body's own equipment schedule prints a year beside the serial (Norcross, Georgia; Wayne Township, New Jersey; the year sits in a row labelled Year Manufactured on 3, and under a column headed Year on 2, 2 of which the document does not define), 2 name an equipment type, 1 of them AHU, across 2 equipment types: 5 matched the reading shown first.
No serial with a date published outside this tool has produced a reading through the Lennox legacy 9-character and Lennox all-numeric 10-digit formats yet. No document from the company that built the unit is held for them, so those rules rest on the secondary references this tool records.
Across the Lennox formats on this page, 2 serials with a date published outside this tool produced no reading at all (Winter Park, Florida). A serial this tool reads nothing from is neither an agreement nor a disagreement, so it is counted in neither.
What refrigerant does a Lennox unit use?
By manufacture year: through 1995: R-22; 1996 to 2009: R-22 (R-410A on select premium series); 2010 to 2024: R-410A; 2025 and later: R-454B ducted / R-32 ductless. The refrigerant printed on the nameplate is authoritative; the year-based mapping tells you what is typical for the age, not what is in a specific unit.
How do I look up my Lennox warranty?
The maker's own page: Lennox's own warranty lookup, at www.lennox.com. The page is headed "Lennox Warranty Lookup". This page reads no maker's records and cannot show whether a unit was registered. Enter the serial in the lookup on this page for the build date and the unit's age. No Lennox warranty certificate is held here for a dated term, so the result dates no term, says so, and names what would answer it; a Service Brief carries what is known to whoever works on the unit. One U.S. Consumer Product Safety Commission recall notice this tool matches names Lennox equipment. Where the serial and model entered meet, or may meet, a notice's printed conditions, the result shows that notice first, with CPSC's own hazard and remedy, and compares each condition; where a notice lists models and none was entered, it asks for the model, unless something else entered or read from the serial rules the unit out of that notice. It never says a unit is or is not recalled, and it says nothing when nothing entered meets or may meet one.
Is my Lennox unit still under warranty?
This tool holds Lennox's warranty page but not its certificates. The page links separate certificates for each series, split between units installed before and after February 8, 2022, so the terms for a unit are on the certificate for its series and install date. The result does not work out a dated term for Lennox: no Lennox certificate is registered for that here. Only the maker's records show whether a unit was registered.
Why do some Lennox serial numbers refuse to decode?
Short all-numeric serials are the pre-1973 Lennox style. The two decodings this tool holds for it conflict, and the unit is an antique, so this tool does not decode it.
How old is my Lennox furnace?
Lennox's own Model Numbering Systems bulletin covers its furnaces (its model codes include "Gas furnace multi position"). Enter the furnace's serial above: the result gives the date and age and says which document covers it.
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