How old is my AC unit or heat pump?
The build date is coded into the serial number on the rating plate of the outdoor unit. Choose the brand and type the serial to get the month and year.
Find the age from the serial number
Choose the brand for its date-code chart
- Amana1 serial format
- American Standard5 serial formats
- Armstrong Air2 serial formats
- Bryant1 serial format
- Carrier1 serial format
- Coleman4 serial formats
- Comfortmaker1 serial format
- Daikin1 serial format
- Ducane2 serial formats
- Goodman1 serial format
- Heil1 serial format
- Lennox1 serial format
- Luxaire2 serial formats
- Nordyne1 serial format
- Payne1 serial format
- Rheem1 serial format
- Ruud1 serial format
- Tempstar1 serial format
- Trane5 serial formats
- York2 serial formats
Where is the serial number?
The rating plate of a central air conditioner or heat pump is on the outdoor unit, on the back or side panel near the point where the refrigerant lines and the electrical cable enter.
Sun and weather fade these labels. Shade the plate with a hand and shine a phone light across it at a low angle to read stamped or faded characters.
The indoor coil or air handler has its own rating plate and serial number, and can be a different age from the outdoor unit.
No readable serial number?
- Some rating plates print the manufacture date in plain text. When it is there, use it.
- The plate names the refrigerant, and the refrigerant narrows the age. See the notes that appear with the decoded date.
- An installation invoice, a service sticker or a mechanical permit gives the installation date, which is usually within a year of manufacture.
What the age means
| Equipment | Typical service life |
|---|---|
| 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. The model number decoder reads it for 14 brands.
Questions and answers
How long does this equipment last?
Typical service life: central air conditioner 10 to 21 years and heat pump 15 to 16 years. Water quality, maintenance and how hard the equipment works move a given unit above or below the range.
Is a heat pump serial number read the same way as an air conditioner serial?
Yes for nearly every brand. A heat pump is built on the same lines as the air conditioner and uses the same serial system, so one brand decoder covers both.
Does the outdoor unit date tell me the age of the whole system?
Only of the outdoor unit. The indoor coil, the air handler and the furnace each have their own serial number and may have been replaced at a different time.
Other equipment
- How old is my water heater?Tank and tankless, by serial number
- How old is my furnace?Gas, oil and electric furnaces
- How old is my refrigerator?Refrigerators and freezers
- How old is my appliance?Washers, dryers, dishwashers, ranges
Page last reviewed on October 5, 2026. Method and sources.