October 2004 on: letter, digit, month letter, digit
Newer York serials start with a plant letter. The year is split in two: the 2nd and 4th characters together make the two-digit year, and the letter between them is the month[1][2][3][4].
W 0 K 5 896070 → year 0+5 = 2005, K = September → September 2005
1971 to September 2004: four letters and six digits
The older style is four letters then six digits. The 2nd letter is the month and the3rd letter is the year [1][2][3][5]. Some plates add a letter in brackets at the front, such as “(S)”; ignore it.
E F B M 210830 → F = June, B = 1972 or 1993 → June 1972 or June 1993
The year letters run on a 21-year cycle, so most letters fit two years. The unit’s condition and the age of the house usually make it clear which one you have.
York month letters skip I and J
Unlike most brands, York skips J as well as I, so September is K and December is N[1][2]. An older chart used J for September [5]; we follow the two newer sources. These letters apply to both styles.
| Letter | A | B | C | D | E | F | G | H | K | L | M | N |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
York year letters (older style)
The cycle skips I, O, Q, U and Z. The older chart carries the letters on to 2007, but every other source says the numeric style replaced them in October 2004, so the decoder stops the letters at September 2004.
| Letter | Years |
|---|---|
A | 1971 or 1992 |
B | 1972 or 1993 |
C | 1973 or 1994 |
D | 1974 or 1995 |
E | 1975 or 1996 |
F | 1976 or 1997 |
G | 1977 or 1998 |
H | 1978 or 1999 |
J | 1979 or 2000 |
K | 1980 or 2001 |
L | 1981 or 2002 |
M | 1982 or 2003 |
N | 1983 or 2004 (2004 only to September) |
P | 1984 |
R | 1985 |
S | 1986 |
T | 1987 |
V | 1988 |
W | 1989 |
X | 1990 |
Y | 1991 |
Worked examples
| Serial | Style | How it reads | Made | Example from |
|---|---|---|---|---|
N0L4123456 | Letter, digit, month letter, digit (October 2004 on) | 0 = first digit of the two-digit year; L = month letter (October); 4 = second digit of the two-digit year | October 2004 | InterNACHI forum |
W0A9123456 | Letter, digit, month letter, digit (October 2004 on) | 0 = first digit of the two-digit year; A = month letter (January); 9 = second digit of the two-digit year | January 2009 | InterNACHI forum |
N0D6653823 | Letter, digit, month letter, digit (October 2004 on) | 0 = first digit of the two-digit year; D = month letter (April); 6 = second digit of the two-digit year | April 2006 | PickHVAC |
W0K5896070 | Letter, digit, month letter, digit (October 2004 on) | 0 = first digit of the two-digit year; K = month letter (September); 5 = second digit of the two-digit yearForum dates a W0K58… unit to September 2005; full serial is the Building Intelligence Center example. | September 2005 | Inspector's Journal forum |
EFBM210830 | Four letters + 6 digits (1971 – September 2004) | F = month letter (June); B = year letter (1972 or 1993) | June 1972 or 1993 | InterNACHI forum |
EEHM611744 | Four letters + 6 digits (1971 – September 2004) | E = month letter (May); H = year letter (1978 or 1999) | May 1978 or 1999 | InterNACHI forum |
YHFM321456 | Four letters + 6 digits (1971 – September 2004) | H = month letter (August); F = year letter (1976 or 1997) | August 1976 or 1997 | PickHVAC |
SEBHM062202 | Four letters + 6 digits (1971 – September 2004) | B = month letter (February); H = year letter (1978 or 1999)Printed "(S)EBHM062202"; the parenthesized letter is ignored. | February 1978 or 1999 | Building Intelligence Center |
Where to find the serial number
On the rating plate on the cabinet. Luxaire and Coleman units are made by the same company and read the same way.
What this page doesn’t decode
Two-letter codes from before 1980 (such as “AO” or “DM”). Only one chart describes them, and York told inspectors the old letter positions weren’t used consistently.
Common questions
How do I read the date on a York furnace?
If the serial starts letter–digit–letter–digit, join the two digits for the year and read the letter between them as the month. If it starts with four letters, the 2nd is the month and the 3rd the year.
Why does my York serial give two years?
The older style’s year letters repeat every 21 years. F, for example, is 1976 or 1997.
What does a J in a York serial mean?
York’s month codes don’t use J. If J sits where the month should be, the serial is a different style or was copied wrong.
Not affiliated with York, Luxaire or Coleman. Brand names are used only to say which serials this decoder reads.
Sources
- InterNACHI forum: York A/C & Furnace Serial No Decoding Help (post by John Bowman, 2009-06-22)Used for: Letter, digit, month letter, digit (October 2004 on); Four letters + 6 digits (1971 – September 2004).
- PickHVAC (Rene Langer, 2025-06-03): York HVAC Age: Serial Number DecodingUsed for: Letter, digit, month letter, digit (October 2004 on); Four letters + 6 digits (1971 – September 2004).
- Building Intelligence Center: York HVAC AgeUsed for: Letter, digit, month letter, digit (October 2004 on); Four letters + 6 digits (1971 – September 2004).
- Inspector's Journal forum: York dates off in decoder chart (thread, 2008-08-12)Used for: Letter, digit, month letter, digit (October 2004 on).
- Honest Home Inspections, LLC (hosted by InspectAPedia): How to determine Water Heater and Furnace Age (PDF, last updated 2009-01-06)Used for: Four letters + 6 digits (1971 – September 2004).