Carrier furnace and AC age by serial number

Reviewed 2026-10-155 primary sourcesSee sources

Carrier’s service manuals give the layout: the first two digits are the week, the next two the year, then a letter for the factory and a five-digit unit number. Carrier documents this for its air conditioners and heat pumps.

Covers: Carrier residential air conditioners and heat pumps (24- and 25-series), with Carrier furnaces read the same way where Carrier’s own serial range supports it.

Where to find the serial number

• The serial number is on the rating plate, usually on the outdoor unit and inside the furnace.^[4]
• On Bryant equipment (a Carrier brand), the outdoor unit’s plate is on the back above the service valves and the furnace’s is inside the front door panel.^[5]

Date formats Carrier documents

Week + year + plant letter + numberdocumented for 24/25-series outdoor units

Carrier doesn’t give the century or say how weeks are counted; we read the year within 1990–2089.^[1]

What Carrier says

• Carrier’s legacy furnace program covers 90% furnaces built from 1993 to 2011 with serials from 2993A00001 to 5211A99999. That range fits the week-and-year reading (week 29 of 1993 to week 52 of 2011), but Carrier doesn’t decode furnace serials or explain the letter A.^[3]
• Carrier says the serial number on the rating plate often contains the date of manufacture.^[4]

Worked examples

• 0106E00001: Week 1 of 2006, Collierville plant (Carrier’s example).^[1]
• 0118E00001: Week 1 of 2018, Collierville plant (Carrier’s example).^[2]

What the serial can’t tell you

• Only two plant letters (E and X) are documented; any other letter is unknown.^[1]
• The layout is documented for Carrier 24- and 25-series outdoor units. Carrier’s manuals don’t say whether Bryant, Payne or other Carrier brands use it.^[2]
• Bryant’s own serial layout: Bryant only says where the plate is.
• The meaning of the letter A in Carrier furnace serials.