How to read a Goodman, Amana serial number (find the build date)

Decode a serial number now (works offline).

The rule

Digits 1–2 = year, digits 3–4 = month (01–12). Serials are 10 digits long on current units.

The maker doesn’t publish this rule where I could find it, so it rests on inspector and HVAC-guide sources and may be wrong for some units: Third-party HVAC guide (not the maker).

Worked examples

0408523981August 2004
1811000001November 2018

Applies to: Goodman and Amana furnaces and air conditioners. Always check the result against the label.