ToftThis covers Carrier, Bryant, Payne, Day & Night. The serial number is on the metal data plate. On an outdoor unit it's on the side or back. On a furnace it's inside the cabinet, behind the front door.
Ten characters: four digits, a letter, then five digits. The first two digits are the week of the year and the next two are the year.
Example: 4006A17330 was made in week 40 of 2006.
This is the date the unit was made. It was usually installed soon after, but it can be later. If a serial doesn’t fit any of these patterns, look on the label for a printed manufacture date.
Checked in October 2026.
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