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How old is my Day & Night packaged unit?

Serial number age decoder for Day & Night packaged rooftop and ground units: 1 format era, the decode rule in plain English, transcribed tables, and the official lookup.

Serial number decoder for Day & Night packaged unit

Serial no.

Type the serial from the data plate, not the model number. Nothing is sent anywhere; the tables are in this page.

Format example: 4006A17330

Day & Night packaged unit serial numbers in the 1980 to present format encode the year as digits 3-4 (2-digit year; century by context, 1980+) and the week as digits 1-2 (01-53) (source: building-center.org).
Example: serial 4006A17330 decodes to week 40 of 2006.
Day & Night's official lookup at dayandnightcomfort.com returns warranty / registration lookup.

Format eras

1980 to present VERIFIED
####A#####digits 3-4 (2-digit year; century by context, 1980+)

How to read the serial

1980 to present formatVERIFIED

Shape ####A##### · example 4006A17330 · confidence high

Year: digits 3-4 (2-digit year; century by context, 1980+)
Week or month: week = digits 1-2 (01-53)
Plant: letter at position 5 (plant/line code; table not published)

Example: serial 4006A17330 decodes to week 40 of 2006.

Trap: Same 4-digit-letter-5-digit shape as Lennox style 1 (Lennox = plant,plant,YY,month-letter). Two-digit year needs century disambiguation (e.g. 06 = 2006 vs 1986); use ANSI/date on plate.

Listed under Carrier in the source; Day & Night is named in that format's family.

Where the data plate is on a packaged unit

On the cabinet exterior near the electrical access panel, or inside the panel door.

General guidance, not brand-specific: the owner's manual or the installer can point to the exact spot. See the data plate guide.

Official lookup: the authority

Open the official Day & Night lookup takes serial number; returns warranty / registration lookup; URL verified live

This site is a reference built from published tables. The manufacturer's own lookup wins whenever the two disagree.

What we could not confirm

Historic Carrier/BDP brand, now marketed by ICP (icpusa.com our-brands). Styles 4006A17330 (WWYY-L, Carrier style 1) and 850304091 (YYMM 1980s). NOTE dayandnight.com is an unrelated company; the HVAC site is dayandnightcomfort.com. Building-center calls 4006A17330 'nine character' - it is ten.