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Carrier family

How old is my Day & Night air conditioner?

Enter the serial number from the label. The date comes from Day & Night's documented serial rules, not a guess.

Look for “Serial No.” or “S/N” on the label. Spaces and dashes are fine.

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How to read a Day & Night air conditioner serial number

  • Week + year, plant letter, sequence (1988 onward)

    Example: 4006A17330 (Carrier) was made in October 2006. In Carrier, Bryant and Payne serials the first two digits are the week (40) and the next two are the year (2006). The letter after them is the factory.

Not decoded yet: Pre-1988 Carrier, Bryant and Payne formats (month letters, week + year letter, all-numeric) are not decoded because sources disagree.

Where to find the serial number

The rating plate is on the outdoor unit, usually on the side or back of the cabinet near the electrical disconnect or the refrigerant line connections.

Don't open the unit's panels to look for it. If the plate is faded, the indoor coil or the installer's paperwork may also list the model and serial.

How long does a air conditioner last?

A typical air conditioner lasts about 10–15 years. That's a general estimate: maintenance, usage, climate and installation all matter, and age alone doesn't tell you a unit's condition. Some manufacturer pages cite 15–20 years for well-maintained systems.

Range from NAHB / Bank of America, Study of Life Expectancy of Home Components (2007, archived copy) and Carrier: AC replacement.

Day & Night air conditioner recalls

No Day & Night air conditioner recalls were found in U.S. Consumer Product Safety Commission data when this page was checked (2026-09-29). A decoded result checks your model number live.

Questions

How can I tell how old my Day & Night air conditioner is?
Find the serial number on the rating plate and enter it above. Day & Night air conditioners use the Carrier family serial format, which includes the manufacture date. For example, 4006A17330 was made in October 2006: In Carrier, Bryant and Payne serials the first two digits are the week (40) and the next two are the year (2006). The letter after them is the factory.
Where is the serial number on a Day & Night air conditioner?
The rating plate is on the outdoor unit, usually on the side or back of the cabinet near the electrical disconnect or the refrigerant line connections. Don't open the unit's panels to look for it. If the plate is faded, the indoor coil or the installer's paperwork may also list the model and serial.
How long does a air conditioner usually last?
A typical service life is about 10–15 years. That's a general estimate: maintenance, usage, climate and installation all matter, and age alone doesn't tell you a unit's condition.
Do Carrier, Bryant and Payne air conditioners use the same serial format?
Yes. Day & Night, Carrier, Bryant and Payne use the same serial-number conventions (Carrier family), so the same decoding rules apply.
How reliable is the result?
The Carrier family rules come from documented sources, but they're in Beta while we check more real-world examples, so results are capped at medium confidence. If a serial doesn't match a documented format, we say so instead of guessing.

Same serial format: Carrier air conditioner, Bryant air conditioner, Payne air conditioner

Other Day & Night equipment: furnace, heat pump

Sources

Rules last reviewed 2026-09-28. These rules are in Beta while we verify more real-world examples, so results are capped at medium confidence.

Manufacture dates are decoded from manufacturer serial-number conventions and available documentation. Serial formats can change. Verify critical equipment information with the manufacturer when necessary.