I know this has been convered before, but I wanted to see if anyone has new info. I am looking for an A/C servo for my 79 300D. I do not want to spend big bucks. Not a new one, aluminum or plastic. I want to fix the thing, even if it doesnt last a very long time. Should I try fixing the crack? what do you guys think?

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Andrew Villasenor
805-720-5057
1984 300D turbo 5-speed manual(daily driver)
ALL MY DIESELS RUNNING WVO
Everything is for sale for the right amount
Ebay Store

once it cracks coant gets into the mecanicals and corrodes it and shorts out the electrical motor inside it.

Unless you are a mechanical marvel you would be wasting your time...when they sieze up the ACC amp usually blows...

both items are about $450 plus core charge.

short of bypassing it there is no real easy fix.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

In my old 300CD, I tore my AC servo apart, and was actually able to get it to work somewhat, but I broke the little plastic plunger, so then the whole thing was trash. What happened on mine, is that there is this little clip, and that fell off, so the plunger wasn't working right, but I broke the plunger in the prosess.

Bypassing the servo can be done, the problem is just finding the proper brass fittings, I think I spent about $20 when I bypassed mine, the only probelm is that the fan is on high, and the heat comes from the defrost vents...

I saw a bypass kit on ebay recently but I can't find it now. I guess such a thing does exist.

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1974 240D 3.0L 4(M) - 250K -OM617.910 + 300D FW + Rajay turbo power!
1977 6.9 3(A) - 84k

Just go to a good plumbing supply store, they should have everything there, I believe Fast Lane has the electronic servo bypass valves now, too, I think they are about $700, but look like they are well worth it...

FYI:

http://cgi.ebay.com/ebaymotors/MERCEDES-AC-SERVO-107-116-123-450SL-SEL-300D-240D_W0QQitemZ7999836242QQcategoryZ33699QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Ya, I saw that one on ebay. I might just do that. I called my MB parts guy and he said that his cost just went up $100 on the new alum. ac units. Thanks for the advice.

__________________
Andrew Villasenor
805-720-5057
1984 300D turbo 5-speed manual(daily driver)
ALL MY DIESELS RUNNING WVO
Everything is for sale for the right amount
Ebay Store

The whole thing can be bypassed for probably less than $30. Take the servo out. T off of the console switch with a vacuum connection going to the vacuum switch behind the glove box (bue-green color line). Install a mechanical shut-off valve controlled by a cable on the line going into the heat exchanger. Run a cable into the drivers side to open/shut the valve for heat/defrost. Run a switch to mount inside for the A/C on/off. You will probably also need a new auxilliary heater pump (about $100).

You will wind up with both heat/defrost and A/C. Not as elegant a original but a helluva lot cheaper. The only issue is the fan will run on low whenever the engine is running. Also I have nothing coming out of the center vents but I do have air coming our of the side and defrost vents. I just have to figure out how to turn the fan low off.

It can be done easier than that.
No shutoff, no switch, no aux pump, no problem:
http://www.peachparts.com/shopforum/showthread.php?t=110502&highlight=bypass
Been running this way for over a year, plenty of heat on demand.
If I push both of the two top buttons, I get heat out of front vents too.

__________________
Think Alternative Energy!
300CD '80 (now gone but not forgotten...)

were is the A/C servo amp located?

__________________
Andrew Villasenor
805-720-5057
1984 300D turbo 5-speed manual(daily driver)
ALL MY DIESELS RUNNING WVO
Everything is for sale for the right amount
Ebay Store

Also, if a servo does not have any cracks in it, what is the testing procedure to see if it is good, asuming that you are dealing with a junk car.

__________________
Andrew Villasenor
805-720-5057
1984 300D turbo 5-speed manual(daily driver)
ALL MY DIESELS RUNNING WVO
Everything is for sale for the right amount
Ebay Store

Pull your glove box liner out...its there and a little smaller than a pop tart. Likely you will see smoked components on it through the ventilation holes.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

That is really involved.....and I wouldn't know where to start...even with a manual in front of me....short of sticking it in and seeing it work...I am certain someone will give you a far better answer than that one....mine was split like an over ripe tomato and siezed....I never went through the procedure though i have read it.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche