The serial number on the rating plate usually carries the build date — but each brand encodes it differently, and few publish how. Every layout here comes from the manufacturer’s own documents or official recall records. Pick your brand and paste the serial.
We only decode a brand when the date layout comes from the manufacturer’s own documents, or when official records (government recall notices, manufacturer bulletins and recall pages) pair enough real serial numbers with build dates to confirm it. Brand pages list every source.
| Brand | Serial date decodable? | Covers |
|---|---|---|
| Amana | Yes — confirmed by official records | Amana-branded US equipment built by Goodman (10-digit serials, 2003 on) |
| American Standard | Yes — confirmed by official records | newer serials that start with a two-digit year (2010 on) |
| Bryant | Yes — manufacturer documentation | outdoor AC and heat pump units (shown in Bryant Evolution service manuals) |
| Carrier | Yes — manufacturer documentation | outdoor AC and heat pump units |
| Daikin | Yes — confirmed by official records | Daikin-branded US equipment built by Goodman (10-digit serials, 2003 on) |
| Goodman | Yes — confirmed by official records | 10-digit Goodman serials from 2003 on (AC, heat pumps, furnaces, air handlers, coils) |
| Heil | Yes — manufacturer documentation | current ICP variable-speed outdoor units; older Heil serials use a different, unpublished layout |
| Lennox | Yes — manufacturer documentation | current Lennox serials (plant, year, month letter, unit number) |
| Rheem | Yes — confirmed by official records | serials with an M date code (about 1992-2008) |
| Ruud | Yes — confirmed by official records | serials with an M date code (about 1992-2008) |
| Trane | Yes — confirmed by official records | newer serials that start with a two-digit year (2010 on) |
| Payne | No — format not published | |
| York | No — format not published |
Third-party “decoders” for those brands circulate widely, but none cites the manufacturer, so we don’t reproduce them.
The build date tells you which refrigerant and efficiency rules the unit was made under, whether it is likely still under the parts warranty, and how it compares with current equipment. To check whether it is the right size, run the AC sizing check; to read its tonnage, use the model number decoder.