Hello,

Does a Climate Control unit off a 1985 W126 Part# 126 830 02 85 work in a 1983 W123 300D with the original unit's part # 123 830 12 85? They physically look the same. I was told it you won't get all the function to work 100%

Thanks in advance for your answers.

The units are not the same. The W126 has one more vacuum actuator than the W123. So you definitely will lose some function if you were to install the W123 unit in a W126. But going the other way might work.

Other way around using 1983 300SD controller in 1985 300D seemed to work fine, though I have not yet checked control of A/C system.

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Der Panzermann und Fraulein Fahrvergnuegen

1991 420SEL 201K "The Big Blue One"
1985 300DT 205K chassis/285K engine nee California emissions "Goldbug"
1983 300TDT 255K "The Womble"
1983 300 DT 214K "Sea Sprite"-Rear-ended a truck
1983 300SD 285K "The Donor" Gave his life so that others can live
1980 500SL Euro 105K "Der Panzer"