Furnace and AC age by serial number

Pick the brand on the unit’s rating plate. Each page decodes that manufacturer’s published serial layout and lists the eras it covers.

Goodman and AmanaGoodman and Amana warranties say the first four digits of the serial number are the year and month of manufacture. Decode yours and see what it can’t tell you.
LennoxRead the plant, year and month from a Lennox serial number like 5921C05716, using Lennox’s own serial numbering documents.
CarrierCarrier serial numbers start with the week and year of manufacture. Decode a Carrier air conditioner, heat pump or furnace serial and see what Carrier does and doesn’t confirm.
Trane and American StandardTrane and American Standard don’t publish a residential serial decoder. Here is how they tell owners to find the manufacture date instead.