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HVAC Serial Number Lookup: Decode Your Unit’s Age by Brand (2026)

Homeowner inspecting an outdoor AC condenser during an HVAC serial number lookup

By The HVAC Brief Editorial Team · Independent HVAC trade desk. Every figure is traced to federal data or the Code of Federal Regulations. · Last updated: October 2026

How does an HVAC serial number lookup tell you a unit’s age? The manufacture date sits in the first four or five characters. Goodman writes year then month, Carrier and Bryant write week then year, and Lennox writes a plant code, the year and a month letter. Check the rating plate first: some print the date outright.

5 of 10Residential brand families whose serial date code we could trace to the manufacturer’s own literature or a CPSC recall notice. The other five stay unverified. Source: The HVAC Brief review of manufacturer and CPSC documents, October 2026.

Key Takeaways

  • Goodman, Amana and Daikin: the first four digits are year and month (YYMM); Goodman’s own example is 1306 = June 2013.
  • Carrier’s service literature decodes 01 06 E 00001 as week 01, year 2006, plant E (Collierville, TN).
  • Lennox puts a plant code first: in its 2025 handbook, 59 = Marshalltown, IA (Heating), then the year, then a month letter (A = January).
  • Trane Technologies’ Oxbox decoder reads 19 34 6 0205 J as 2019, week 34, day 6, unit 205.
  • With no installer invoice, Trane and American Standard start the warranty 60 days after the factory manufacture date shown by the serial.
  • ENERGY STAR says to consider replacing a heat pump or AC more than 10 years old, or a furnace more than 15 years old.

HVAC serial number lookup by brand: which characters are the date?

An HVAC serial number lookup works because makers code the build date into the serial, but each brand family orders the characters differently. The table lists only layouts traced to the manufacturer’s own literature or a federal recall notice.

Brand family Date characters Manufacturer’s example Status and source
Goodman, Amana, Daikin 1 to 4: year, then month (YYMM) 1306… = June 2013 Verified: Goodman and Daikin warranty certificates
Carrier, Bryant 1 to 4: week, then year (WWYY); 5: plant letter 01 06 E 00001 = week 1, 2006 Verified: Carrier service manual; Bryant 575J instructions (2023)
Lennox 1 to 2: plant; 3 to 4: year; 5: month letter 59 21 C… = March 2021 Verified: Lennox product specifications (2025)
Trane, American Standard 1 to 5: year, week, day of week 19 34 6 0205 J = 2019, week 34, Saturday Partial: Trane Technologies’ Oxbox decoder; CPSC notices
Rheem, Ruud Older units: 4 digits after “M” = week, then year M3592 = week 35, 1992 Partial: CPSC notices (1999, 2009); current W-prefix layout unconfirmed
York, Coleman, Luxaire Not verified None found No manufacturer key located
Armstrong Air, AirEase, Ducane, Concord Not verified None found Allied Air sites carry no key
Heil, Tempstar, Comfortmaker, Day & Night Not verified None found ICP manuals checked; no key
Frigidaire, Maytag, Gibson, Intertherm Not verified None found Nordyne literature host offline

Shared ownership does not mean a shared layout. Heil belongs to Carrier and Armstrong Air to Lennox, as our brand ownership map shows, but no document applies the parent’s key to them, so we leave them blank.

The rating plate on the outdoor unit carries the model and serial numbers.
The rating plate on the outdoor unit carries the model and serial numbers. AI illustration.

Where is the serial number on a furnace or outdoor unit?

On the outdoor unit, the rating plate is usually on the back or side near the refrigerant valves; on a furnace, it is inside the cabinet behind the front panel. Split systems carry two serials, and the halves can differ in age.

  1. Outdoor unit: Goodman says the plate is “generally found slightly above the refrigerant valves on the back side”; Trane places its label on the top, right-rear of the outdoor condenser.
  2. Furnace: Trane puts the label on the right or left panel. Lennox says to remove the top-front service panel and look on the left interior wall or the blower deck, depending on whether the unit is 80% or 90% AFUE.
  3. Switch the furnace off before removing a panel, and copy the whole string, letters included.

How do you read each verified format?

Find your brand, then read the characters in the order its maker documents. Reading a Lennox or Carrier serial with Goodman’s year-first rule gives the wrong year.

Goodman’s furnace warranty states: “The first four digits of the serial number (YYMM) on the unit indicate the manufacture date.” Its example: a serial beginning 1306 was built in June 2013. Daikin’s DM97MC furnace specification repeats the sentence, and Goodman calls the serial “a ten digit code.”

Carrier’s 25VNA8 service manual decodes 01 06 E 00001 as week of manufacture, year, manufacturing site (E = Collierville, TN; X = Monterrey, Mexico) and serial. Bryant’s 575J instructions (2023) use the same order: positions 1 to 2 are the week “(fiscal calendar)”, 3 to 4 the year (“23” = 2023). A serial starting 2318 is week 23 of 2018.

Lennox leads with a plant code: 15, 17, 18 and 19 are Saltillo, Mexico; 20 is Gainesville, FL; 56 is Stuttgart, AR; 57, 58 and 59 are Marshalltown, IA. Then come the two-digit year and a month letter (A = January, B = February, C = March), then a 5 or 6 digit number. Lennox’s example, 59 21 C… 05716, is a March 2021 build.

Trane Technologies’ decoder for its Oxbox line reads 19 34 6 0205 J as 2019, week 34, day 6 (1 = Monday, so Saturday), the 205th unit that day, J for Oxbox. We found no Trane-branded residential key, so treat this as strong evidence. A 2005 CPSC notice on Trane and American Standard units said the first four digits gave “the year, fiscal week and day of manufacture,” an older one-digit-year form.

For older Rheem equipment, a 1999 CPSC notice states: “The date code is the four digits following the letter ‘M’ in the unit’s serial number,” week first, then year. A 2009 Rheem oil-furnace notice uses the same “M” code. Rheem’s archived age calculator lists newer samples such as W031833465 without stating a rule, so we leave that layout unconfirmed.

Manufacturer example serials, decodedGoodman, Amana, DaikinYYMM13Year 201306Month: JunexxxxxxSequenceCarrier, BryantWWYY01Week 106Year 2006EPlant00001SerialLennoxPlant, YY, month59Plant: IA21Year 2021CMarch05716Unique no.Trane (Oxbox key)YY, WW, day19Year 201934Week 346Saturday0205Unit 205JBrandRed = the part most often misread. Sources: Goodman, Carrier, Lennox and Trane Technologies documents listed below.
Four example serials as printed in the makers’ own documents: Goodman furnace warranty (1306 = June 2013), Carrier 25VNA8 service manual (01 06 E 00001), Lennox product specifications 2025 (59 21 C… 05716) and Trane Technologies’ Oxbox decoder (19 34 6 0205 J). Goodman’s full example digits after 1306 are not published, so they are shown as x.

Which brands’ serial number lookup could not be verified?

Five families stayed unverified: York, Coleman and Luxaire; the Allied Air brands (Armstrong Air, AirEase, Ducane, Concord); the ICP brands (Heil, Tempstar, Comfortmaker, Day & Night); the Nordyne brands (Frigidaire, Maytag, Gibson, Intertherm); and Payne. For these, use the maker’s warranty lookup or call the brand with the full serial.

The only Johnson Controls serial key we opened covers chillers, not home equipment. Allied Air and ICP literature carries no date key, and the old Nordyne literature server no longer resolves.

Correction

Decoder sites in the top results disagree with the manufacturers. One states that Lennox uses “the same WWYY format as Carrier”; Lennox’s own handbook puts a plant code first and uses a month letter. Another says Goodman serials start with “a letter indicating plant location”; Goodman’s warranty says the first four digits are YYMM.

Do the decoding rules hold up against recall records?

Yes, for the two brands we could test. Federal recall notices, such as the CPSC’s 2017 Goodman furnace recall, pair serial ranges with sale dates, and the documented keys decode those ranges to dates just before or inside the sale windows.

CPSC recall Serial range Sold Decoded with the maker’s key
Goodman, Amana, Daikin furnaces (May 2, 2017; about 4,100 units) Begins 1609, 1610, 1611, 1612 Sept 2016 to Jan 2017 YYMM: Sept to Dec 2016
Trane, American Standard, Ameristar furnaces (Nov 8, 2016; about 17,700 units) Begins 16304 to 16324 July to Aug 2016 YY WW D: 2016, weeks 30 to 32
Rheem electric furnaces and air handlers (Feb 16, 1999) Date codes 3592 to 4595 Not stated WWYY: week 35 of 1992 to week 45 of 1995

Recalls are defined by serial range, so keep the full string. Check any unit against our HVAC recall tracker before an inspection or home sale.

Does an HVAC serial number show the install date?

No. The serial records when the unit was built, not when it went into your home. Manufacturers bridge the gap with fixed assumptions: if you cannot show an installer’s invoice, the warranty clock starts a set time after the serial’s manufacture date.

60 daysTrane and American Standard: warranty start after the factory manufacture date when the invoice lacks a start-up dateTrane GW-OTDR-2401B
90 daysRheem, Ruud, WeatherKing: manufacture date “as verified by the product’s serial number” plus 90 daysRheem limited warranty
3 monthsGoodman and Daikin: assumed install date when the original date cannot be verifiedGoodman PW-CFURNU
60 daysGoodman’s online registration window for its 10-year parts warranty (not required in California, Florida or Québec)Goodman warranty overview 08-25

Registration windows also run from installation: Bryant’s lookup page says units registered within 90 days get a 10-year parts warranty instead of 5, and Luxaire’s warranties “revert to warranties with shorter timeframes” after 90 days. Our guide to what an HVAC warranty actually covers explains the parts-versus-labor split.

Some plates skip the decoding entirely. Trane and American Standard packaged units recalled in 2005 had identification plates showing “the year, month and day of manufacture,” so read the whole plate before decoding. Goodman and Bryant both run online warranty lookups; Bryant’s asks for the serial and shows the general parts warranty on record.

An aging outdoor unit: the serial number tells you how old it really is.
An aging outdoor unit: the serial number tells you how old it really is. AI illustration.

What to do once you know your HVAC age by serial number

Compare the decoded year with two federal benchmarks. ENERGY STAR suggests considering replacement when a heat pump or air conditioner is more than 10 years old, or a furnace or boiler more than 15 years old. Age alone is not a verdict: compare it with typical equipment lifespans and your repair history.

  1. Decode both halves of a split system. An outdoor unit from 2008 paired with a 2019 furnace is two different decisions.
  2. Check the refrigerant line on the plate. American Standard’s owner’s guide says that from January 1, 2010, R-22 “will no longer be used as a manufacturer-installed refrigerant as required by federal regulation,” which is why an older condenser raises R-22 supply and repair questions.
  3. If replacement is on the table, weigh replacing now against waiting and price it with our 2026 replacement cost data.
HVAC serial number lookup: six numbers that matter5 of 10Brand families traced to a makeror CPSC date-code documentSource: The HVAC Brief, Oct 20261306Goodman serial start: builtJune 2013 (year, then month)Source: Goodman warranty60 daysTrane and American Standardwarranty start after build dateSource: Trane GW-OTDR-2401B90 daysRheem, Ruud, WeatherKingwarranty start after build dateSource: Rheem limited warranty10 yearsHeat pump or AC older than:ENERGY STAR replacement checkSource: ENERGY STAR15 yearsFurnace or boiler older than:ENERGY STAR replacement checkSource: ENERGY STARthehvacbrief.com · Sources listed in full at the end of this article
Sources: The HVAC Brief brand review (October 2026); Goodman furnace limited warranty PW-CFURNU; Trane and American Standard base limited warranty GW-OTDR-2401B; Rheem, Ruud, WeatherKing limited warranty; ENERGY STAR, “When is it time to replace?”

How we researched this

Research date: October 8, 2026. We consulted 42 documents and cite 22: manufacturer warranties and service literature as posted in October 2026, and six CPSC recall notices from 1999 to 2017. A brand counted as verified only if a manufacturer document or CPSC notice stated the key; decoder sites, forums and contractor blogs were excluded. The dataset (serials.json, CC BY 4.0) is reviewed quarterly.

Frequently asked questions

Is there an app or website for an HVAC serial number lookup?

Use the manufacturer’s own warranty lookup. Bryant’s asks for the serial number and shows the parts warranty on record, and Goodman links one from its registration FAQ. Third-party apps apply decoding rules that, for half the brand families we checked, no manufacturer document confirms.

How do I find furnace age by serial number?

Find the rating plate inside the cabinet; Lennox says to remove the top-front service panel. Read the first four or five characters with your brand’s key: Goodman, Amana and Daikin use year then month, Carrier and Bryant week then year, Lennox a plant code, year and month letter.

How do I read a Goodman serial number?

Goodman’s warranty says the first four digits are year and month (YYMM), so a serial beginning 1306 was built in June 2013. Daikin documents repeat the rule. A 2017 CPSC recall listed Goodman furnace serials beginning 1609 to 1612 that sold from September 2016, matching it.

How old is my Trane or American Standard unit?

Trane Technologies’ Oxbox decoder reads the first five characters as year, week and day, so 19346 means 2019, week 34, Saturday. A 2016 CPSC furnace recall listed Trane and American Standard serials beginning 16304 to 16324, sold in July and August 2016, which fits that layout.

Does the serial number show if my unit is under warranty?

Not on its own. Warranties normally start at installation. Without an invoice, Trane and American Standard start 60 days after the manufacture date, Rheem 90 days after, and Goodman and Daikin assume installation 3 months after. Goodman requires online registration within 60 days for its 10-year parts term, outside California, Florida and Québec.

What if the serial number plate is missing or unreadable?

Check the paperwork. Goodman says dealers may attach the shipping box’s traveler label to the homeowner’s documents, Luxaire points owners to the dealer invoice, and Trane’s warranty expects the installer’s invoice to list all model and serial numbers. Your installing contractor may also have it on file.

Sources

  1. Goodman. “Gas furnace limited warranty PW-CFURNU.” https://apps.goodmanmfg.com/brochures/files/55f9bce7bd52bPW-CFURNU.pdf Accessed October 2026.
  2. Goodman. “How to confirm the model/serial #.” https://www.goodmanmfg.com/resources/faq/registration/how-can-i-confirm-the-model-and-serial-numbers-for-my-cooling-system Accessed October 2026.
  3. Goodman. “Product warranty overview 08-25.” https://apps.goodmanmfg.com/brochures/files/68c18eb7cdc96PM-WARRCHRT-G_08-25%5B23%5D.pdf Accessed October 2026.
  4. Daikin. “Guide specifications WGS-U09-2020, DM97MC.” https://daikincomfort.com/docs/default-source/dm97mc/wgs-u09-2020-dm97mc-dc97mc_d4740a6d-3a4e-4813-b296-5a5e9a0588e2.pdf Accessed October 2026.
  5. Carrier. “25VNA8/24VNA9 service manual.” https://www.shareddocs.com/hvac/docs/1009/Public/01/25VNA8-24VNA9-4SM.pdf Accessed October 2026.
  6. Bryant. “575J installation instructions II575J-16-25-02.” https://www.shareddocs.com/hvac/docs/1005/Public/0F/II575J-16-25-02.pdf Accessed October 2026.
  7. Bryant. “Warranty lookup.” https://www.bryant.com/en/us/warranty-lookup/ Accessed October 2026.
  8. Lennox. “Model number identification, R-454B and R-32 products.” https://www.lennox.com/dA/d1bf319d00/ehb_model_id_r-454b-r32_2503.pdf Accessed October 2026.
  9. Lennox. “Model and serial numbers, heating.” https://www.lennox.com/residential/support/faqs/model-serial-numbers-heating Accessed October 2026.
  10. Trane Technologies. “Oxbox serial number decoder.” https://www.tranetechnologies.com/content/dam/common/oxbox/serial-number-decoder/Oxbox_Serial_Number_Decoder.pdf Accessed October 2026.
  11. Trane. “Locating the serial numbers.” https://www.trane.com/content/dam/Trane/residential/downloads/SNInstructions-Trane.pdf Accessed October 2026.
  12. Trane. “Base limited warranty GW-OTDR-2401B.” https://www.trane.com/pdf/GW-OTDR-2401B.pdf Accessed October 2026.
  13. American Standard. “Owner’s guide, outdoor units.” https://www.americanstandardair.com/content/dam/Trane/residential/downloads/manuals/22-5213-WEB01_Outdoor_Units.pdf Accessed October 2026.
  14. Rheem. “Limited warranty, Rheem, Ruud, WeatherKing.” https://files.myrheem.com/webpartners/ProductDocuments/11E9DDA7-869E-4FAA-8671-6FC924B29050.pdf Accessed October 2026.
  15. Rheem. “How old is my air conditioner” (archived copy). https://web.archive.org/web/2024id_/https://www.rheem.com/how-old-is-my-air-conditioner/ Accessed October 2026.
  16. CPSC. “Rheem electric furnaces and air handlers recall” (1999). https://www.cpsc.gov/Recalls/1999/cpsc-rheem-manufacturing-announce-recall-to-repair-electric-furnaces-and-air-handlers Accessed October 2026.
  17. CPSC. “Rheem oil-fired furnaces recall” (2009). https://www.cpsc.gov/Recalls/2009/rheem-recalls-to-repair-oil-fired-furnaces-due-to-fire-hazard Accessed October 2026.
  18. CPSC. “American Standard gas-electric units recall” (2005). https://www.cpsc.gov/Recalls/2005/CPSC-American-Standard-Companies-Announce-Recall-of-Gas-Electric-HeatingCooling-Units- Accessed October 2026.
  19. CPSC. “Trane recalls furnaces” (2016). https://www.cpsc.gov/Recalls/2017/Trane-Recalls-Furnaces Accessed October 2026.
  20. CPSC. “Goodman recalls furnaces” (2017). https://www.cpsc.gov/Recalls/2017/Goodman-Recalls-Furnaces Accessed October 2026.
  21. Luxaire. “Warranty registration.” https://www.luxaire.com/residential-equipment/warranty-and-registration Accessed October 2026.
  22. ENERGY STAR. “When is it time to replace?” https://www.energystar.gov/saveathome/heating-cooling/replace Accessed October 2026.

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