On York units built since 2004, the serial number encodes the date in the first four characters: position 2 and position 4 are the two digits of the year, and position 3 is a month letter (A = January through M = December, skipping I). A serial starting W0K5 decodes to October 2005 — the 0 and 5 combine to year 05, and K is October. Older York units (1971–2004) use an all-letter date code instead. The same formats apply to Coleman, Luxaire, and Fraser-Johnston, which are the same Johnson Controls equipment under different labels. This guide covers both eras with examples.
Free York Serial Number Decoder
The fastest route is our free HVAC Age Decoder. Select “York” (or Coleman / Luxaire), enter the serial number — and for pre-2004 units, the model number too — and get the manufacture date, age, and estimated remaining lifespan. The model number matters for older York serials because the letter codes repeat; more on that below.
Where to Find Your York Serial Number
| Equipment Type | Data Plate Location |
|---|---|
| Air conditioner (outdoor condenser) | Side panel of the outdoor unit, near the refrigerant service valves |
| Heat pump (outdoor unit) | Same as the condenser — side panel |
| Furnace (indoor) | Inside the cabinet behind the front/blower door, on a sidewall |
| Air handler | Behind the access panel, near the blower |
| Package unit | Exterior panel, typically near the electrical disconnect |
Some York serials print with a parenthesized letter prefix like (S). Ignore that prefix when decoding — the date code starts after it.
Style 1: York Serial Numbers from 2004 to Today
Modern York serials follow a letter–digit–letter–digit opening:
- Position 1: Factory letter
- Position 2: First digit of the two-digit year
- Position 3: Month letter (A–M, skipping I)
- Position 4: Second digit of the two-digit year
| Letter | Month | Letter | Month |
|---|---|---|---|
| A | January | G | July |
| B | February | H | August |
| C | March | J | September |
| D | April | K | October |
| E | May | L | November |
| F | June | M | December |
Worked Examples
Example 1: W0K5896070
- W = factory
- 0 and 5 = year 05 → 2005
- K = October
- Manufactured October 2005
Example 2: N1D8123456
- N = factory
- 1 and 8 = year 18 → 2018
- D = April
- Manufactured April 2018
The split-year arrangement is the part that trips people up: the two year digits are not adjacent. Read positions 2 and 4 together.
Style 2: York Serial Numbers from 1971 to 2004
Older York serials open with a run of letters:
- Position 1: Factory letter
- Position 2: Month letter (A–M, skipping I — same table as above)
- Position 3: Year letter
The year letters advanced one per year and then repeated after about 24 years, so each letter maps to two possible years:
| Letter | Years | Letter | Years |
|---|---|---|---|
| B | 1971 or 1995 | M | 1981 |
| C | 1972 or 1996 | N | 1982 |
| D | 1973 or 1997 | P | 1983 |
| E | 1974 or 1998 | R | 1984 |
| F | 1975 or 1999 | S | 1985 |
| G | 1976 or 2000 | T | 1986 |
| H | 1977 or 2001 | U | 1987 |
| J | 1978 or 2002 | V | 1988 |
| K | 1979 or 2003 | W | 1989 |
| L | 1980 or 2004 | X | 1990 |
| A | 1993 | Y | 1991 |
| Z | 1992 |
Example: WAKM011379
- W = factory
- A = January
- K = 1979 or 2003
- Manufactured January 1979 or January 2003
How to break the tie between the two candidate years
- Model number: Feature and efficiency changes place a model line in one era or the other. Our HVAC Age Decoder accepts the model number for exactly this reason.
- Refrigerant type (cooling equipment): An R-22 unit could be either era, but SEER ratings on the data plate help — a 13+ SEER unit is the later candidate.
- Common sense: A unit still running today is far more likely to be the later year. A 1979 condenser still cooling a Texas home in 2026 would be a museum piece.
Either way, a Style-2 serial means the unit is at least 20 years old — which in Central Texas heat puts it past typical AC and heat-pump lifespan. See How Long Does an AC Unit Last in Texas?.
York, Coleman, Luxaire: What’s the Difference?
All three (plus Fraser-Johnston) are built by Johnson Controls on shared platforms — same factories, same serial format, same core components. The differences are distribution channel and badge, the same arrangement as Rheem and Ruud or Carrier and Bryant. Decode a Coleman or Luxaire serial exactly as you would a York.
Frequently Asked Questions
The letters on my data plate are faded. Any alternatives?
Check the installation paperwork or any service stickers inside the blower door — technicians often write the serial on invoices. Your original installer may have it on file. Johnson Controls dealer support can sometimes look up a unit by model and address.
Does the serial number show the size (tonnage)?
No — capacity lives in the model number. For York cooling models, look for a 2-digit number divisible by 6 or 12 (024, 036, 048, 060 = 2, 3, 4, 5 tons). Our What Size AC Do I Need? guide explains sizing.
My York furnace is from the 1990s. Should I replace it before it fails?
A 30-year-old furnace is past its expected life (how long furnaces last), and heat-exchanger integrity becomes a genuine safety question at that age. Have it inspected before every heating season at minimum, and plan the replacement on your schedule rather than waiting for a January failure. Our furnace replacement cost guide covers current pricing.
Get Expert Help With Your York System
Texas Temp Masters services York, Coleman, and Luxaire equipment across Central Texas — repairs, maintenance, and straight answers on repair-versus-replace.
Helpful resources:
- HVAC Age Decoder — decode any York-family serial number, with model-number disambiguation for older units
- Repair or Replace? — run the numbers on an aging unit
- Best HVAC Brands for Texas — where York fits in the market
Call us at (817) 704-0706 for York AC repair, furnace service, or replacement quotes. Same-day appointments available across Central Texas.
