Carrier serial number lookup: age of a furnace, AC or heat pump
The serial number is on the rating plate: on the back of an outdoor unit, or inside the front door panel of a furnace. In a Carrier serial the first two digits are the week and the next two digits are the year.
Decode a Carrier serial number
How to read a Carrier serial number
Week and year, first four digits
The first two digits are the week of the year and the next two digits are the year.
Shape: four digits, a letter and five digits.
4006A17330 reads as week 40 of 2006 (around October).
References disagree on when this layout began: some say 1980, others the mid or late 1980s. The rating plate behind the example also prints “Date of manufacture Oct 2006”, which matches week 40.
Where to find the serial number
On an air conditioner or heat pump the rating plate is on the back of the outdoor unit, near the refrigerant service valves.
On a furnace it is on the inside of the front door panel. Turn the knobs on the front of the furnace and pull the panel toward you.
If the serial number does not decode
- Many Carrier rating plates also print the date of manufacture. When it is there, read it directly.
- Gas furnaces from the 1980s and 1990s print the year of the safety standard they were certified to, for example “Z21.47” followed by a year. The furnace was built in that year or a few years after it.
- Serials from before the mid-1980s start with a letter or have nine digits. Those layouts rest on a single reference and are not decoded here.
- The manufacturer can confirm the date from the serial: Carrier 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. Carrier model number tonnage shows where the digits sit and reads them for you.
About Carrier
Carrier was part of United Technologies from 1979 and has been an independent company, Carrier Global, since 2020. Bryant and Payne joined Carrier in 1955 and share its serial system. Heil, Tempstar and Comfortmaker, which Carrier has owned since 1999 through International Comfort Products, use a different one.
Brands that share this serial system: Bryant, Payne.
Questions and answers
Which characters in a Carrier serial number show the date?
The first two digits are the week of the year and the next two digits are the year. This applies to units built since the 1980s.
Sources
- Building Intelligence Center: Carrier HVAC age (independent reference): https://www.building-center.org/carrier-hvac-age/
- McGarry and Madsen Inspection: age of a Carrier heat pump or air conditioner from the serial number (independent reference): https://www.howtolookatahouse.com/Blog/Entries/2018/7/how-can-i-tell-the-age-of-a-carrier-heat-pump-or-air-conditioner-from-the-serial-number.html
- Electrical Forensics (Ray Franco, forensic engineer): air conditioner date codes (independent reference): https://www.electrical-forensics.com/HVAC/AirConditionerDateCodes.html
- CPSC recall: Carrier rooftop units, serials 1214P to 3317P sold March 2014 to September 2017 (US Consumer Product Safety Commission): https://www.cpsc.gov/Recalls/2018/Carrier-Recalls-to-Repair-Commercial-Rooftop-HVAC-Units-Due-to-Fire-Hazard-Recall-Alert
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.