Help with age please

Armstrong Furnace G1N80BU100D20C-1A SER # 1605MO1535

16TH WEEK 2005??

I get Dec. of 2005 - After 1974 Armstrong used the first two digits as the manufacturing plant, the third and fourth as the year, and the letter as the month. :slight_smile:

I believe, like Lennox, the first 2 numbers are the manufacturing plant, second 2 are the year and the fifth slot is the month (A through M minus I).

So, December of 2005.

Thank you for the help!


You are correct on the dating.

The name was revived to Armstrong Air after Lennox purchased the climate control line from Magic Chef. The Air conditioning division was sold to Lennox in 1988 and renamed Armstrong Air.