Week + year + factory
4006A17330
Week 40, 2006 (around October).
Furnaces & AC / Carrier

Look for “Serial” or “S/N” near the service connectionsDark = year, orange = month or week.
Week 40, 2006 (around October).
Supports the 10-character, four-digits + letter + five-digits layout used since 1980. Earlier layouts are excluded. The indoor and outdoor units can have different manufacture dates.
References checked 2026-10-26.
Independent reference tool, unaffiliated with Carrier. Sources & method