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HVAC date-code guide

Day & Night serial number lookup

Day & Night is an ICP regional brand. Modern equipment commonly carries the ICP serial structure with year and week near the front.

Parent
International Comfort Products / Carrier Global
Common code
A plant letter is followed by a two-digit year and two-digit production week (LYYWW).
Reviewed
August 8, 2026

Instant equipment lookup

Decode the manufacturing date

Runs on this device
Equipment type

Using A plant letter is followed by a two-digit year and two-digit production week (LYYWW).

Type exactly what is printed. Spaces and dashes are ignored.

Optional: add model number for capacity cluesAdd model

Model decoding is labeled as a clue unless the exact format is documented.

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EQUIPMENT DATA
MODEL24ABC636A003
SERIAL5019X30312
WeekYear

See exactly how the code was read

SerialAtlas highlights the date characters, names the matching rule, and shows alternative interpretations when the code is ambiguous.

  • Current age calculated automatically
  • Confidence and rule source shown
  • Optional model-capacity clue

How to read a Day & Night serial number

A plant letter is followed by a two-digit year and two-digit production week (LYYWW). SerialAtlas removes spacing and punctuation, then applies only the documented rule families mapped to Day & Night. The lookup remains in the browser.

Try this documented-style exampleE142320733Load example

Equipment covered

  • air conditioners
  • heat pumps
  • furnaces
  • air handlers
  • packaged systems

Commercial, imported, very old, specialty, and private-label equipment can use a different code. Confirm the full rating plate before accepting a result.

Where to find the rating plate

  • Outdoor condenser or heat-pump cabinet, usually near the service valves
  • Inside the furnace or air-handler access panel
  • On the packaged-unit rating plate
  • Near the electrical disconnect or wiring diagram

Why more than one date can appear

Two-digit years and repeating letter cycles can point to more than one era. SerialAtlas ranks the plausible dates but keeps materially different alternatives visible. Label design, refrigerant, installation records, and product literature can resolve the era.

Source and verification

Inspector Handbook open reference data (CC BY 4.0). Independently implemented and reviewed August 8, 2026.

Open reference source

What this result does not prove

A manufacture date is not an installation date, warranty decision, recall match, condition assessment, or replacement recommendation. Confirm high-stakes decisions with the manufacturer or a qualified professional.