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Old 07-05-2012, 04:10 PM
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JamesDean JamesDean is offline
Electrical Engineer
 
Join Date: Apr 2005
Location: NE Ohio
Posts: 5,038
Inside the box: W126 Automatic Climate Control. First Gen.

Hello everyone,

Forum member mccauleybil sent me his climate control unit to see if I could repair it.

He sent:

126 830 02 85 Climate Control Push Button Unit
126.032 - 380SE
126.033 - 380SEL
126.037 - 500SEL
126.043 - 380SEC
126.044 - 500SEC
126.120 - 300SD

000 822 09 03 Temperaturregler.
126.032 - 380SE
126.033 - 380SEL
126.037 - 500SEL
126.043 - 380SEC
126.044 - 500SEC
126.120 - 300SD

I took apart the PBU and discovered that there really isnt much to go wrong inside this unit! There are a few relays, diodes and resistors and thats it!

What I did see that could go bad are a large amount of solder points on the back.

The temp setting wheel also contains some interesting circuitry. There is a small 10k pot mounted at the center of the wheel. There are also three traces that the unit uses as a potentiometer as well. Now from all the other trace style pots that I've seen there has always been a carbon coating present, however this was not the case. I'm not sure if its simply eroded away over the years or simply was never present in the first place... I dont have another PBU to disect for comparison.


PBU Pictures:





















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82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

Last edited by JamesDean; 07-05-2012 at 06:37 PM.
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