American Standard serial number lookup: age of a furnace, AC or heat pump
The serial number is on a label on the back of the outdoor unit or on the side of the furnace. American Standard shares Trane’s serial system: since 2010 the first two digits are the year and the next two are the week.
Decode an American Standard serial number
How to read an American Standard serial number
American Standard has used 5 serial formats. Find the one that matches the shape of your serial.
Two-digit year, then week
The first two digits are the year and the next two are the week.
Shape: ten characters starting with four digits.
130313596L reads as week 3 of 2013 (around January).
Trane counts weeks on its own fiscal calendar, so the month shown for a week is approximate.
One-digit year, then week
The first digit is the last digit of the year, 2 for 2002 through 9 for 2009. The next two digits are the week.
Shape: nine characters starting with three digits.
91531S41F reads as week 15 of 2009 (around April).
The rating plate behind the example also prints “MFR DATE 4/2009”, which matches week 15. Trane counts weeks on its own fiscal calendar, so the month shown for a week is approximate.
Year letter, then week
The first letter is the year. The letters are not in alphabetical order, so use the chart. The two digits after the letter are the week.
Shape: nine characters: a letter, two digits, then six more characters.
R1742DWBF reads as week 17 of 2000 (around April).
Year letter
- W 1983
- X 1984
- Y 1985
- S 1986
- B 1987
- C 1988
- D 1989
- E 1990
- F 1991
- G 1992
- H 1993
- J 1994
- K 1995
- L 1996
- M 1997
- N 1998
- P 1999
- R 2000
- Z 2001
The rating plate behind the example also prints “MFR DATE 04/2000”, which matches week 17.
Year letter at the end
The letter in the seventh position is the year. The serial gives no month or week.
Shape: six digits followed by one letter.
123456T reads as 1981.
Year letter
- A 1980
- O 1980
- B 1981
- T 1981
- C 1982
- U 1982
One reference swaps T and U. Five others agree that T is 1981 and U is 1982.
Year digit, then month letter
The first digit is the last digit of the year, 1 for 1971 through 9 for 1979. The letter after it is the month, A for January through M for December with the letter I left out.
Shape: a digit, a letter, a dash and four digits.
2D-1234 reads as April 1972.
Month letter
- A January
- B February
- C March
- D April
- E May
- F June
- G July
- H August
- J September
- K October
- L November
- M December
Where to find the serial number
On an air conditioner or heat pump the serial label is on the top right of the back of the outdoor unit. On a packaged unit it is on the rear panel.
On a furnace the label is on the right or left side panel. On an air handler or an indoor coil it is on the front panel.
If the serial number does not decode
- American Standard heating and cooling equipment is built by Trane. Recall notices list the two brands together with the same serial ranges.
- Most rating plates print the manufacture date in a field marked “MFR DATE”. When it is there, read it directly.
- Count the characters to tell the recent layouts apart: ten characters with a two-digit year since 2010, nine characters with a one-digit year from 2002 to 2009.
- Trane and American Standard equipment has at times been built by other manufacturers. A unit built by another company follows that company’s serial format.
- The manufacturer can confirm the date from the serial: American Standard 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. Trane model number tonnage shows where the digits sit and reads them for you.
About American Standard
American Standard Heating and Air Conditioning is a brand of Trane Technologies. It is separate from the American Standard plumbing-fixture business, which was sold in 2007. American Standard and Trane equipment shares one serial system.
Brands that share this serial system: Trane.
Questions and answers
Which characters in an American Standard serial number show the date?
The first two digits are the year and the next two are the week. This applies to units built since 2010.
Why does my American Standard serial number look different?
American Standard has used 5 serial formats: two-digit year, then week (built since 2010); one-digit year, then week (built 2002 to 2009); year letter, then week (built 1983 to 2001); year letter at the end (built 1980 to 1982); year digit, then month letter (built 1971 to 1979). The decoder tries each one.
The decoder shows more than one possible year. Which one is right?
Part of the American Standard 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.
Who makes American Standard heating and cooling equipment?
American Standard heating and cooling equipment is built by Trane. Recall notices list the two brands together with the same serial ranges.
Why are the year letters out of order?
From 1983 to 2001 the first letter of the serial was the year, but the letters were not assigned alphabetically: W is 1983, X 1984, Y 1985, S 1986, then B for 1987 through P for 1999, R for 2000 and Z for 2001. The chart on this page lists every letter.
Sources
- Building Intelligence Center: Trane HVAC age (independent reference): https://www.building-center.org/trane-hvac-age/
- Parts Town: Trane serial number lookup guide (independent reference): https://www.partstown.com/cm/resource-center/guides/gd2/trane-serial-number-lookup
- CPSC recall 17-709: Trane and American Standard furnaces, serials 16304 to 16324 sold July and August 2016 (US Consumer Product Safety Commission): https://www.cpsc.gov/Recalls/2017/Trane-Recalls-Furnaces
- CPSC recall 05-104: Trane and American Standard gas-electric units, how the serial encodes year and week (US Consumer Product Safety Commission): https://www.cpsc.gov/Recalls/2005/CPSC-American-Standard-Companies-Announce-Recall-of-Gas-Electric-HeatingCooling-Units-
- CPSC recall 01-507: Trane Voyager units, serials R21 to R33 built June to August 2000 (US Consumer Product Safety Commission): https://www.cpsc.gov/Recalls/2001/cpsc-trane-company-announce-recall-of-voyager-heating-and-air-conditioning-systems
- Electrical Forensics (Ray Franco, forensic engineer): air conditioner date codes (independent reference): https://www.electrical-forensics.com/HVAC/AirConditionerDateCodes.html
- Energy Trust of Oregon: furnace age by serial number (independent reference): https://insider.energytrust.org/wp-content/uploads/CPF_Furnace_Age.pdf
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.