York serial number lookup: age of a furnace, AC or heat pump
The serial number is on the label inside the furnace cabinet or on the rating plate of the outdoor unit. In a York serial from October 2004 or later, the second and fourth characters are the year and the letter between them is the month.
Decode a York serial number
How to read a York serial number
York has used 2 serial formats. Find the one that matches the shape of your serial.
Letter, digit, letter, digit
The second and fourth characters are digits. Read together they are the year: 0 and 5 make 2005. The letter between them is the month.
Shape: a letter, a digit, a letter and a digit, followed by six digits.
W0K5896070 reads as September 2005.
Month letter
- A January
- B February
- C March
- D April
- E May
- F June
- G July
- H August
- K September
- L October
- M November
- N December
The month letters skip I and J: K is September, L October, M November and N December. One general chart lists J to M for those four months instead. The two York-specific references agree on K to N. Plant letters: A Apodaca, N Norman, S Source One, W Wichita.
Four letters: plant, month, year, type
The second letter is the month and the third letter is the year. The first letter is the plant and the fourth is the type of item.
Shape: four letters followed by six digits.
WFKM003094 reads as June 2001.
The same code also fits 1980. Month letter
- A January
- B February
- C March
- D April
- E May
- F June
- G July
- H August
- K September
- L October
- M November
- N December
Year letter
- A 1971, 1992
- B 1972, 1993
- C 1973, 1994
- D 1974, 1995
- E 1975, 1996
- F 1976, 1997
- G 1977, 1998
- H 1978, 1999
- J 1979, 2000
- K 1980, 2001
- L 1981, 2002
- M 1982, 2003
- N 1983, 2004
- P 1984
- R 1985
- S 1986
- T 1987
- V 1988
- W 1989
- X 1990
- Y 1991
The year letters A to N each stand for two years, 21 years apart. The letters P to Y stand for one year each, 1984 to 1991. References disagree on whether this layout began in 1971 or 1980. Some plates print one more letter in brackets in front of the four.
Where to find the serial number
On a furnace the label is inside the cabinet, behind the removable front panels.
On an air conditioner or heat pump the rating plate is on the cabinet of the outdoor unit.
If the serial number does not decode
- Tell the two layouts apart by shape. A letter, a digit, a letter and a digit is the current layout. Four letters in a row is the layout used until October 2004.
- In the older layout the year letters A to N each fit two years, 21 years apart. The age of the house, the refrigerant named on the plate or the standard dates in the small print show which one applies.
- York serials from the 1970s that start with only two letters are not decoded here. References disagree on how to read them.
- The manufacturer can confirm the date from the serial: York registration, warranty or serial lookup.
What the age tells you
| Equipment | Typical service life |
|---|---|
| Furnace | 15 to 22 years |
| Central air conditioner | 10 to 21 years |
| Heat pump | 15 to 16 years |
What size is it?
The model number on the same rating plate gives the size: the tonnage of an air conditioner or heat pump, or the heating input of a furnace. York model number tonnage shows where the digits sit and reads them for you.
About York
York was an independent company from 1986 until Johnson Controls bought it in 2005. In August 2025 its residential business, with the York, Luxaire and Coleman brands, passed to the Bosch Home Comfort Group. The three brands share one serial system, which changed in October 2004.
Brands that share this serial system: Luxaire, Coleman.
Questions and answers
Which characters in a York serial number show the date?
The second and fourth characters are digits. Read together they are the year: 0 and 5 make 2005. The letter between them is the month. This applies to units built since October 2004.
Why does my York serial number look different?
York has used 2 serial formats: letter, digit, letter, digit (built since October 2004); four letters: plant, month, year, type (built until October 2004). The decoder tries each one.
The decoder shows more than one possible year. Which one is right?
Part of the York date code repeats, so the serial alone fits more than one year. A manufacture date printed on the rating plate, the print date of the owner’s manual or the installation record settles it. For equipment that is still running, the more recent year is usually the right one.
Sources
- York serial numbers identification sheet, “from history to October 2004” (archived dealer copy) (independent reference): https://web.archive.org/web/20171118111839/http://www.usair-eng.com/Serialnumber.pdf
- Building Intelligence Center: York HVAC age (independent reference): https://www.building-center.org/york-hvac-age/
- McGarry and Madsen Inspection: age of a York air conditioner or furnace from the serial number (independent reference): https://www.howtolookatahouse.com/Blog/Entries/2018/6/how-can-i-tell-the-age-of-a-york-air-conditioner-or-furnace-from-the-serial-number.html
- CPSC recall: York, Luxaire and Coleman furnaces built May to July 2001, serials starting WFKM or WGKM (US Consumer Product Safety Commission): https://www.cpsc.gov/Recalls/2001/cpsc-york-international-corporation-announce-recall-of-gas-furnaces
- CPSC recall: York Diamond 80 furnaces sold May 1994 to July 1996, serials EECM to EGEM (US Consumer Product Safety Commission): https://cpsc.gov/recalls/2000/cpsc-york-international-corp-announce-recall-of-york-international-corporation-diamond-80-furnaces
Formats last checked against these sources on October 5, 2026. Found a serial that does not fit? Send a correction. How formats are verified: method and sources.