a/c age

Carrier: s/n 3691ed06409, Is it 1991?
Also furnance: s/n 0207645696


For Carrier, the first 4 numeric characters are the week and year of production.

So it looks like you’ve got manufacturing dates of 1991 for the Condenser and the Furnace must be brand new (07).

The furnace doesn’t appear to be new.

Its a Janitrol: m/n gmt090-4


It looks like the AHU is from 2002.

Ohhhh, I had thought they were both manufactured by Carrier.

**Janitrol - **Division of Surface Combustion Co. became division of Midland-Ross in 1960, then became division of Tappan in 1977. The Janitrol name was sold to Goodman Mfg. in 1982. Also sold as Goodman, GMC, Sears, Kenmore, and Johnstone.

I can not come up with your exact Model number under any of those companies. The Goodman model numbers come pretty close to the number you supplied, but not exact. The closest I can come is GMP NO 80-4 which was manufactured between 1994 and 2001.

If you can come up with a Serial number (under Goodman) the first two digits are the year. Second two are the month.

I agree, 2002 for the furnace.