I have a 1980 300SD with the dreaded (deaded?) servo unit. Is it possible to swap out this A/C unit with something from another chassis or model?

Will only work if it is an easy-to-medium swap. I'm not a mechanic-expert (although the 300SD is working on that).

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79 300SD - $50 out of pocket purchase
03 Dodge Ram 3500 CTD
2003 VW Jetta TDI

Doubt it is easy to medium.
It has been suggested here that it is only a maybe.
The expectation is that the complete evaporator/heat-exchanger box
behind dash would have to be swapped out.
Then all the electrical for the newer model. Having a donor car handy would be a plus.

The $550 to $750 replacement system was on my list as a choice. It seemed, in the long run, to be the best no hassle sure to work a long time solution.
I plan on driving my car another 10 years.
But... I was able to get my hands on an aluminum bodied servo valve and amplifier for maybe $300 (the aluminum valve is currently $600). It worked and now I am pleased. Part of the installation included repair of broken vaccum line going to the old valve.

When my valve originally broke I went several years with just a bypass hose for winter driving so I could get heat.
My AC worked even with a busted valve.

So, if money is tight, bypass for less than $20 to get heat.
If you can acquire a replacement servo (and possibly the amp), it is a no hassle drop in repair.
If the price for those parts starts getting up around $500, get the kit and never worry about it again.

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80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250

Do you have links for those procedures. I have also a W116. and i was exploring the possibility to have one of those 700 bucks electronic servo retrofit or even better... a manual european AC from a 6.9.
How does the bypass work? only for the heat or you can also bypass for the cooling? right now i only have defrost.

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Aquilae non capunt muscas! (Eagles don't hunt flies!)


1979 300SD Black/Black MBtex239000mi
1983 300TD euro-NA. White/Olive Cloth-MBtex 201000mi. Fleet car of the USA embassy in Morocco
1983 240D Labrador Blue/Blue MBtex 161000mi

I would like links too because my 300sd A/C unit also failed.

The compressor is frozen up and I don't know what else it will need but the mechanic said it would cost $500 to $800 to fix and that he would not recommend doing it. He said just drive it as is. That is OK in winter but in So.Cal. not a good plan in the summer.

The body of this car is in excellent condition with no rust and it has 210,000 miles. I think it could easily go another 100,000 miles because it does not use oil or smoke.

The A/C system has been worked on before so may need the servo kit too. My mechanic is very honest so I can ask him and he will give an honest answer.

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DCM

1977 240d
1980 300sd
1987 Chevrolet Suburban

Here is a bypass kit from mercedes source. It's in the interactive catalog under electrical / early climate control. I Haven't used it but I think that is the way I'm gonna go.



http://www.**************.com/

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Sonny


86 190D N/A 2.5L Auto 265k "Ruby" -Sold-
79 300D 242k "Condi" my first -sold- RIP
2013 chevy sonic hatchback - had to for work

Rhodes 2010 PM'ed you.
Thanks

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1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
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1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD

You can try the manual AC system from a 73-75 116. That's a 3 month project for me

Sixto
93 300SD

first remove the servo from the vehicle. Place it on a hard flat surface, such as an anvil. Take a 5lb. sledge hammer and proceed to beat it into pieces no larger than 1/4", or until you have exhausted your repetoire of profanities. now go back to the car and install a manual coolant valve and call it a day. Just my $0.02

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1980 300d on veggie

Was Mercedes the only brand that used those servo's?

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).

Chrysler used that servo in their high end models before Mercedes. Apparently it almost destroyed the company due to blown motors from coolant leaks. Too bad Mercedes hadn't done their homework and found this out!

Just replace it with the digital servo kit. It will work forever and wont leak. It will make you smile.

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1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

The answer to his question is yes, they are the same on the W123, W116, and R107. You can use a spare unit from any of those.

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Adam Lumsden
(83) 300D
Vice-President of the MBCA International Stars Section

Regarding Chrysler use of the servo system....it was concurrent with the Mercedes use...so there was not much real world experience with the system and it's issues prior to wholesale deployment.

Also, I have an aluminum servo, amplifier, replacement vacuum harness, vacuum motors and push button panel that I am selling from my 1977 450SEL. I had replaced all these parts in the late 1990's early 2000 time frame when I was going through my A/C. All were working fine when engine was overheated (blown head gaskets). I would like $300 for all.
Thanks,
Lee Zook

Ron, can you elaborate on how the digital unit works?
I realize that you no longer need the CC amp, but how about the aux water pump?
Where does the unit physically go? From where do you physically control it?

What exactly does it allow you to control? Only heat?

Thanks

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD