The AC doesnt work in my 1985 300D. I filled it up with r134 and it doesnt turn on. The blower fan works but no cold air.

I have done plenaty of AC work on Fords and Hondas but it's my first time working in an MB ac system.

The compressson doesnt turn on. I jumped the compressor clutch to make it turn on manualy and it did turn on but still no cold air inside.

Any help is apreciated.

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1985 300D : the clean one 180k miles - Now passed onto my parents.
2000 E39 M5
2002 e46 330xit
1991 mustang notch (project)
1970 chevelle (project)

did it work before converting to 134A? I have done several conversions without any issues.

The '85 is unique in the fact that it's the first year with a Klima relay. You'll need to start there to see if the Klima is providing the signal to the clutch.

Unfortunately, it's a completely different pin configuration then what I'm familiar with on the SDL's.

On an '85 model, the AC won't work if the tach is inop. Is your tach working? If not, do a search on "Klima" {search titles} and there is a pic of which pins to jump to bypass an inop. tach.....

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

I didnt work when I bought it.

The tach does work.


I will look Klima up guyz.

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1985 300D : the clean one 180k miles - Now passed onto my parents.
2000 E39 M5
2002 e46 330xit
1991 mustang notch (project)
1970 chevelle (project)

This thread should be required reading for all of us. Brian Carlton has REALLY written a great piece. Even if you pin out #'s aren't the same, it is a step by step model for us. Read everything.
http://www.peachparts.com/shopforum/showthread.php?t=131216

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Well this really looks like a headache and a half.

__________________
1985 300D : the clean one 180k miles - Now passed onto my parents.
2000 E39 M5
2002 e46 330xit
1991 mustang notch (project)
1970 chevelle (project)

It's really not all that difficult.

The only question is whether the W123 uses the same socket configuration for the Klima on the '85 as found in this thread:

http://www.peachparts.com/shopforum/showthread.php?t=131216

After some research, I found this info:

http://www.peachparts.com/shopforum/showpost.php?p=1452692&postcount=15

This indicates that socket #10 receives a 12V signal from the CCU. However, I'm not sure if this is correct. All the vehicles from '86 forward use a ground signal from the CCU.

So, you start with the basics. Do you get a ground signal from the CCU on socket #10???? when you ask for a/c?

Or, do you get a 12V signal on socket #10 when you ask for a/c?

Yes or no?

Does the ground signal go to open when you set the CCU to economy?

Or, does the 12V signal disappear when you set the CCU to economy?

Yes or no?