How do I tell the age of a Fedders furnace or air conditioner from the serial number? Although the Fedders brand is used for window units nowadays, this encoding only applies to when they manufactured unitary (split) systems years ago. The second letter of the serial number indicates the year of manufacture (from 1966 to 1977): A = 1966 B = 1967 C = 1968 D = 1969 E = 1970 F = 1971 G = 1972 H = 1973 I = (not used) J = 1974 K = 1975 L = 1976 M = 1977 An ancient Fedders unit we recently inspected had the serial number AH11877, indicating that it was manufactured in 1973. The home was built in 1973, which provided a secondary verification of the manufacture date indicated by the serial number
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How do I tell the age of a Fedders furnace or air conditioner from the serial number?
Although the Fedders brand is used for window units nowadays, this encoding only applies to when they manufactured unitary (split) systems years ago. The second letter of the serial number indicates the year of manufacture (from 1966 to 1977):
A = 1966 B = 1967 C = 1968
D = 1969 E = 1970 F = 1971
G = 1972 H = 1973 I = (not used)
J = 1974 K = 1975 L = 1976 M = 1977
An ancient Fedders unit we recently inspected had the serial number AH11877, indicating that it was manufactured in 1973. The home was built in 1973, which provided a secondary verification of the manufacture date indicated by the serial number
https://www.manualslib.com/brand/fedders/air-conditioner.html