HVAC Reference Tool
HVAC Serial Number Lookup
Pick the brand, paste the serial number, and get the manufacture date with a character-by-character explanation, the unit's age, the refrigerant era it was built in, and, for the 20 brands whose warranty certificates are held here, the warranty term the certificate prints for that build date, or a plain refusal naming what would answer it. Where one of the 21 U.S. CPSC recall notices held here matches what you enter, the notice comes first.
Paste the serial and we run every documented format at once. Where two brands read the same digits as different years, you will see both readings instead of one guess.
Starting the decoder. The serial formats further down this page are already loaded, so you can read yours off them now.
7 of the 41 decode rules rest on a single secondary reference. Where two agree, that is weaker evidence than it looks: secondary references copy one another, and agreement between two is not a manufacturer document being read. Be clear on what that is worth: 17 of the 41 decode rules here rest on reference compilations rather than on a document from the company that built the unit. Formats whose documentation conflicts are declined rather than guessed. The date stamped or printed on the data plate, where present, always outranks a serial decode.
After the Date: the Next Question, Worked Out
Where a maker runs a warranty lookup, it answers for a unit registered with it. These are the questions that come after it, and what the result on this page does with each, for the unit you enter.
Is any of my unit's warranty still running?
For the 20 brands whose warranty certificates are held here, the result works out the parts term the certificates print for the unit's build date where held editions dated before and after the build agree, and where an edition gives its term only to listed series, once a model in one of them is entered; it names the edition and quotes its clause, or says why it cannot and what would answer it. Where an edition starts the term at installation, the install month gives the month it runs to. It never says covered or not covered: only the maker's records show whether a unit was registered, and the certificate's own conditions come back as questions to ask.
I cannot show when it was installed. Is the warranty over?
Where every certificate edition held for the unit prints a start for a unit whose install date cannot be shown, and the longest parts term any of them prints had already run out counted from that start, the result says so in its own line and quotes the maker's clause. Where the edition starts the term from installation when that can be shown, the line says an install date that can be shown changes it; where the edition starts it from manufacture whatever the install date, the line says that instead.
The maker's warranty lookup found nothing, or wants a model number I do not have. What now?
This lookup reads the serial on its own. It asks for the model number where a certificate edition gives its term only to listed series, and where a CPSC recall notice this tool holds lists models and nothing else entered or read from the serial rules the unit out of it. Where it cannot work out a term it says so about this unit, says why what this tool holds does not reach it, and names what would answer it.
The house is being sold. What passes to the next owner?
Where the result works out a term, answering the owner question "Being sold now" adds a line for the next owner, read from the certificate's own terms for a later owner where the edition prints them, or saying it cannot date one and naming what would answer it. The question is asked wherever that answer adds the line.
The house is rented out. Does the maker's warranty still apply?
Answer how the building is used with "Home, not lived in by its owner" and the result reads each held certificate edition by what it prints about a home its owner does not live in, rather than by the row for a home its owner lives in. The question is asked where an edition held for the unit prints its own words on such a home or gives commercial use a different term, and it is asked wherever the answer changes a date, the status or whether a term may still be running.
Is there a recall on my air conditioner or furnace?
This tool holds 21 U.S. Consumer Product Safety Commission recall notices for residential heating and cooling equipment from brands its decoder reads. When the brand, serial and model entered meet or may meet one of those notices' printed conditions, the result shows that notice first, with CPSC's own hazard and remedy, and compares each condition with what was entered; where a notice lists models and none was entered, it asks for the model, unless something else entered or read from the serial rules the unit out of that notice. It never says a unit is or is not recalled, cannot show whether a unit has already had CPSC's remedy, and shows nothing when nothing entered meets or may meet one of them; CPSC's own site lists every recall.
A technician is coming, or I am the technician. What do I hand over?
The Service Brief that comes with the result is the unit's paper: a card, a text to send and a PDF, recomputed from its link whenever it is opened, the link carrying only the unit and the answers given. It prints one next action chosen by what is known (a reported stop first, then a recall notice whose every model and serial condition is met by what was entered and, where this tool reads the notice's printed sale window against the build year, whose window did not close before the unit was built, then the warranty). If the reader says who is at the unit, and no stop was reported, it names one step for that person: a homeowner or renter is pointed at sending the brief ahead of the technician's visit, a technician is pointed at the maker's own service document for the unit on the AC not cooling check, in technician mode with the maker's warning first, where one held here covers it, or, where none does, at leaving the customer a PDF copy; someone buying, selling or inspecting the home is pointed at answering the owner question "Being sold now" where that adds a line for the next owner, and, once it is answered, at saving that line with the brief for the home's file, or, where the owner question adds nothing more, at the home's file; a landlord or property manager is pointed at the rental question where its answer can change the certificate's answer, or, where it cannot, at the unit's records, and anyone at a unit that is not theirs at sending the brief to whoever owns or looks after it. That answer changes no fact, verdict or warning, and every one of these steps is described here to everyone.
How Serial Number Formats Work, by Brand Family
HVAC brands cluster into manufacturing families that share plants, data plates, and serial formats. Learn one family's rule and you can date the brands in it, with the one exception the note under the table names. The rightmost column shows the low-GWP A2L refrigerant each family moved to in the 2025 transition.
| Brand family | Serial format | Where the year is | 2025+ refrigerant |
|---|---|---|---|
| Carrier, Bryant, Payne, Day & Night | 4 digits + letter + 4-6 digits | Digits 3-4 (digits 1-2 are the week) | R-454B (Puron Advance) |
| Heil, Tempstar, Comfortmaker, Arcoaire, KeepRite, Airquest | Plant letter + year pair + week pair + 5 digits (4 digits on Arcoaire and Comfortmaker units from 1988 to 1992) | First digit pair after the letter (year comes first, the reverse of Carrier) | R-454B |
| Trane, American Standard, Ameristar | 9 chars (2002-2009) or 10+ chars (2009 on, per Trane) | Leading letter (1980-2001), leading digit (2002-09), digits 1-2 (09 and 2010 on) | R-454B |
| Goodman, Amana, Daikin unitary | 10 digits | Digits 1-2 (digits 3-4 are the month) | R-32 |
| Lennox | 4 digits + month letter + 5 or 6 digits | Digits 3-4 (the letter is the month) | R-454B ducted, R-32 ductless |
| Armstrong Air, AirEase, Ducane, Concord | 4 digits + month letter + 5 digits | Digits 3-4 | R-454B |
| Rheem, Ruud, WeatherKing, Sure Comfort | Letter + 9 digits | Digits 4-5 (digits 2-3 are the week) | R-454B |
| York, Luxaire, Coleman, Fraser-Johnston, Guardian | Letter-digit-letter-digit + 6 digits | The two digits read together (second letter is the month) | R-454B |
| Intertherm, Miller, Gibson, Frigidaire, Maytag + Nortek brands | 12 or 13 characters | Characters 4-5 (6-7 are the month) | R-454B |
| Mitsubishi Electric | 9 characters | First digit = last digit of the year (decade from refrigerant) | R-454B |
| LG | Digit + 2 digits + sequence | First digit = last digit of the year (digits 2-3 are the month); LG's Multi V manuals also print a two-digit year | R-32 |
| Samsung | 10-11 or 15 characters | Year letter seventh from the end, after a final letter (Samsung's own rule) | R-32 |
| Gree; MrCool (Gree-built) | Digits-first serials | Digits 3-4 (digits 1-2 are the week) | R-32 Gree, R-454B MrCool |
| Fujitsu, Senville, Pioneer | Fujitsu and Senville sequential, no date; Pioneer date-coded at positions no Pioneer document this tool holds gives | Use the stamped date code or MFG DATE field on the unit | R-32 (Fujitsu) |
The nastiest trap in this table: Carrier-family serials are week-first (4006A = week 40 of 2006) while the ICP brands owned by the same corporation are year-first (4006A on a Heil would be week 6 of 2040, which is impossible, or year 2040, also impossible; but 9414B reads as 1994 week 14 on a Tempstar and week 94 of 2014, invalid, on a Carrier). Both readings exist only where each pair is at once a valid week and a year this tool can resolve. On every brand but one the nameplate settles it. Day & Night is the exception: it was a Carrier BDP brand and later an ICP brand, so it carries both layouts and its own nameplate cannot choose between them. This tool shows every valid reading, and the MFG DATE field on the data plate, where present, has the final say.
Serial Number Lookup by Brand
Open the dedicated decoder page for your brand, with its exact serial format, refrigerant timeline, and warranty context.
Nortek / Nordyne family
Allied Air family
Trane family
Janitrol (legacy)
Daikin
Lennox
Mitsubishi Electric
LG
Samsung
Gree
Midea
MrCool
Bosch
Bard
Friedrich
GE Zoneline
Worked Examples
Carrier 4006A17330
Four digits, a letter, then four to six digits: the dominant Carrier-family style since about 1980. Digits 1-2 are the week (40), digits 3-4 the year (06), the letter is a plant code, and the rest is the production sequence. Week 40 of 2006 lands in early October. A 2006 Carrier sits in the Puron transition window (1996-2009) when both R-22 and R-410A lines were sold, so the nameplate refrigerant field decides which one this unit holds. That makes it about 20 years old.
Trane R1742DWBF
Nine characters starting with a letter: the 1980-2001 Trane style. The leading R maps to 2000 in Trane's year-letter table, and digits 2-3 are the week (17), so this unit was built in week 17 of 2000, late April. Two letters in that table sit out of alphabetical order: S is 1986 and Z is 2001. That is deliberate rather than a transcription slip, and a chart that puts those two letters in alphabetical order gives a different year for both. A 2000 Trane is R-22 era equipment. That makes it about 26 years old.
Goodman 9704011000
Ten digits, no letters: the Goodman family style used since at least 1997, shared by Amana and Goodman-built Daikin unitary equipment. Digits 1-2 are the year (97), digits 3-4 the month (04): April 1997. The month slice must land in 01-12, which is how the decoder rejects wrong readings of this format. That makes it about 29 years old.
York W1G7123456
Letter, digit, letter, digit, then six digits: the York/Johnson Controls style since October 2004, shared by Luxaire, Coleman, Fraser-Johnston, and Guardian. The oddity is that the year digits are split: position 2 (1) and position 4 (7) read together as 17, so 2017. The second letter is the month: G is July (I and J are skipped). The leading W is the Wichita, Kansas plant. A 2017 York is R-410A equipment. That makes it about 9 years old.
Rheem W291013412
A letter then nine digits: the Rheem family style, shared by Ruud, WeatherKing, and Sure Comfort. This format encodes week and year, not a month: positions 2-3 are the week (29) and positions 4-5 the year (10), so week 29 of 2010, mid-July. That is the first R-410A year in Rheem's own record. The same decode covers Ruud serials letter for letter.
Why Honest Decoders Show Multiple Dates
Serial formats were designed for factories, not for lookups two decades later, and some genuinely cannot be pinned to one date. York's 1971-2004 year letters repeat every 21 years, so YHFM321456 is August of 1976 or 1997. Mitsubishi serials, and LG serials as LG's 2021 service bulletins describe them, carry only the last digit of the year, leaving the decade to the refrigerant or model generation; LG's Multi V manuals print production-start serials (1802xxx for February 1, 2018) that read as a two-digit year and month, so an LG serial that reads both ways is shown both ways. Rheem's digits-first style has two published readings that disagree on whether the leading pair is a week or a month (the year is certain either way). This tool's rule for all of these: run every documented reading, discard the ones that fail validity checks (weeks over 53, months over 12, years in the future), and rank what survives instead of presenting a coin flip as a fact. Formats whose documentation is outright contradictory, like the 22-digit Midea and MrCool serials, are declined with an explanation rather than guessed.
The rules are also checked against the outside world. 327 serial numbers beside which someone other than us published a date have been read, drawn from 48 separate documents published by 8 bodies: a federal regulator, six public bodies and one surplus marketplace. 264 of them produced a dated reading that counts toward a format's check, against 15 of the 41 formats this decoder documents; 18 more produced a reading that is shown and not counted, because a seller entered the year, or the document does not record the unit as a heating or cooling unit; 45 produced no reading at all under this tool's formats. For 7 of the 264, the published year and this tool's reading disagree. Where someone outside this tool wrote down a different year for a unit, that year is shown here rather than dropped. It is that publisher's record for the unit, and a schedule or a listing can carry a replacement, system or lot year rather than the build year. The MFG DATE on the unit's data plate is the build date. The documents behind the checks are listed in the source receipt below.
Frequently Asked Questions
How do I tell how old my AC or furnace is from the serial number?
54 of the 57 brands this tool documents carry a build date in the serial in a layout it reads, but the position varies by brand family. On Carrier, Bryant, and Payne the first four digits are week then year (4006A = week 40 of 2006). On Goodman and Amana the first four digits are year then month (9704 = April 1997). On Trane, a leading letter maps to 1980-2001 and leading digits to 2002 and later. On Rheem and Ruud the week and year follow the leading letter. Pick your brand in the decoder above and it applies the right rule, including the ambiguous cases where two readings are possible. For a furnace, the date is called its age only where a maker document held here dates that brand's furnaces (33 brands); each brand page says whether it does, and the result says so for your serial.
Where is the serial number on an HVAC unit?
On an outdoor condenser or heat pump, the data plate is a metal or foil sticker on the side panel, usually near the refrigerant service valves. On a gas furnace, it is inside the cabinet: remove the front door and look on the blower housing or the inner side wall. On mini splits, check the right side or underside of the indoor head and the side panel of the outdoor unit. The serial is the one labeled S/N or SERIAL.
Is my unit still under warranty?
Terms differ by maker and by certificate edition. This tool holds 82 warranty certificate editions for 20 brands (Day & Night, Heil, Tempstar, Comfortmaker, Arcoaire, KeepRite, ICP / Inter-City Products, Airquest, Carrier, Bryant, Payne, York, Luxaire, Coleman (HVAC), Fraser-Johnston, Goodman, Amana, Rheem, Ruud, WeatherKing). For those, where held editions are dated both before and after the build and agree (and, where an edition gives its term only to the series it lists, the model is one of them), the result works out the base parts term and the dated windows, each with the edition it rests on and the maker's own words; where not, it says so. For other brands it works out no dated term; where this tool holds the maker's published terms, it prints them beside that refusal, labelled, and the brand page names the document. Only the maker's records show whether a unit was registered.
What refrigerant does my unit use, based on its age?
It depends on the brand family, and this tool reads the decoded year against that family's own timeline rather than against one industry rule. The boundaries are not shared: across the 23 families whose record this tool holds names a refrigerant, there are 9 distinct timelines, with era boundaries falling in 1996, 2006, 2008, 2010, 2013, 2024 and 2025, and only 3 of them change over in 2006. What does hold is the newest era: for the 22 families whose record runs to the present it begins in 2024 or 2025 and is an A2L refrigerant, R-454B or R-32 depending on the family. The exception is Janitrol, whose record stops at 1992. GE Zoneline names no refrigerant era; the nameplate says which refrigerant the unit holds. Decode the serial above and the tool prints the era for that unit's family and year, with the caveats that family's record carries. The refrigerant printed on the nameplate always wins over any year-based rule.
When should I replace an AC instead of repairing it?
This tool does not make a repair-or-replace call from a serial. What it gives you for that decision is the unit's build date and age, its refrigerant era, for the 20 brands whose warranty certificates are held here the warranty term the certificate prints for that build date (or a plain refusal naming what would answer it), how long the national stock of its equipment type lasted at that age (a population figure from a 2011 LBNL study, never a forecast for the unit), and a check of a replacement quote against the federal efficiency minimum, each with its source. On an R-22 unit: EPA ended U.S. production and import of R-22 on January 1, 2020, and says an existing R-22 system can still be serviced: "After 2020, only recycled, reclaimed, or previously produced HCFC-22 can be used to service existing equipment." Which refrigerant a unit holds depends on its family as well as its year, so read the era the decoder prints above rather than a single cutoff.
How does the 2025 R-454B and R-32 transition affect my existing unit?
Nothing forces you to replace an existing R-410A system: it can legally run and be serviced for its whole life. What changes is economics. Virgin R-410A production is being phased down under the AIM Act, so recharge costs trend up, and since January 1, 2025 a new split system may be installed with R-410A only if all of its specified components (condensing unit, condenser, compressor, evaporator unit and evaporator, as 40 CFR 84.52 defines them) were made or imported before January 1, 2025, so new systems use lower-GWP A2L refrigerants (R-454B or R-32, depending on brand). A2L refrigerants are mildly flammable, which brings new handling rules, room-size charge limits, and leak-detection requirements, but also a GWP 68 to 78 percent lower than R-410A depending on which one.
Why does the decoder show two possible dates for my serial?
Some formats are genuinely ambiguous and an honest decoder says so. York serials from 1971 to 2004 use year letters that repeat every 21 years, so the letter F means 1976 or 1997. Mitsubishi serials, and LG serials as LG's 2021 service bulletins describe them, carry only the last digit of the year, so the decade must come from the refrigerant or the model generation; LG's Multi V manuals print production-start serials (1802xxx for February 1, 2018) that read as a two-digit year and month, so an LG serial that reads both ways is shown both ways. And the ICP brands (Heil, Tempstar) use a layout that looks identical to Carrier's with the digit pairs swapped, so a serial like 1206A can read as week 12 of 2006 or week 6 of 2012 depending on the brand. When more than one reading passes the validity checks, this tool shows all of them, ranked.
Do all brands encode the date in the serial number?
No. Fujitsu and Senville serials are sequential and carry no date, and Pioneer's own warranty says its serial carries the manufacture date without any Pioneer document this tool holds saying where; for those, look for the separate stamped date code or MFG DATE field on the unit, or contact the manufacturer with the serial. Many Daikin mini splits also carry the date in a separate MFG DATE box instead of the serial. And some formats are documented so inconsistently (Midea and MrCool 22-digit serials, legacy Goodman serials ending in P or D) that this tool declines to guess rather than risk a wrong answer.
What does the week number in a serial mean?
Brands like Carrier, Trane, Rheem, and the ICP family encode the week of the year (01 through 53) instead of the month. Week 01 is early January, week 26 lands around late June, and week 52 is late December. The decoder converts the week to an approximate month for readability, and any week value above 53 is impossible, which is one of the checks this tool uses to reject wrong readings automatically.
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