Took the upper cover off the ACC servo and it was full of corrosion, the thing obviously doesn't work and corroded in place. I want to install a manual bypass valve. My fan only work on high/defrost. I'm assuming my servo amp is fried. Getting a new amp should restore the lower fan speeds but since my servo is seized I think it would quickly burn out my amp. Will the fan run on lower speeds if I totally disconnect the servo and cap the vacuum lines?

Anybody know if I can disconnect the servo and still have fan speed control?

I'm not sure anyone ever completely disconnects the servo.
Most just bypass the bottom of the servo and keep everything
else the same. I know of one person who did take the entire thing out and cap all the vacuum lines and from then on had all kinds of vacuum problems.

Maybe just bypass but leave the servo plugged in.

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Ginny in Denver-ish
78 300SD, 265K (mine)

You don't have independent fan speed control now, how would you have it with the servo disconnected? Fan speed is dependent on the control panel settings and sensor chain inputs.

Here is basic reading on how Type II ACC works:
http://www.imperialclub.com/Repair/Lit/Master/281/cover.htm

I also suggest you read this thread:
http://www.peachparts.com/shopforum/diesel-discussion/213332-1980d-complete-servo-removal-then-bypass-bypass.html

There are other threads on your system as well. Keywords for searching will be "servo" / "evil servo" / and "Type II ACC".

There are ways to bypass that system, but none of them leave you with any portion of it fully functional.

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

Thanks for the help, My situationis when I took the plastic cap off the servo (I have the aluminum bodies one). It was full of corrosion and nothing is moving at all. Even if I leave it plugged in it is not doing anything. By the time I get a rebuilt servo and amp I'm getting close to the cost of the solid state one from "unwired". Is the solid state one a good unit? Better than getting a rebuilt servo?

That is a matter of preference, in terms of whether it's a good value.

The important question: was your system working properly in other respects before the servo died? The Unwired kit specifies that the remainder of the system has to be in working order... if there are vacuum issues, or if the pushbutton panel is defective, the kit won't function either.

I do know from reading posts here that the people who have installed the kit seem to be very happy with it. But there are others who would rather spend the equivalent amount and get a new, aluminum-body servo that will probably last 5-10 years.

When I was faced with the choice, I bought the servo sold by Performance Analysis (George Murphy). However, in 20/20, I can't say for sure I would do the same today....

If you need a temporary fix, there is information here and there on installing a manual, cable-operated valve to control coolant flow for heat.

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

so zacharias,wondering why you would have second thoughts about having installed a george murphy rebuild servo?

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95 e320,87 sdl,79 300sd

Nothing to do with the part. Two things:

(1) When I went to install the new servo I realized that the small hoses that run in and out of it were badly deteriorated. Couldn't find them aftermarket, so I had to order them from Mercedes (I wasn't on this list then so didn't know about Phil's expertise in getting stuff like that). One or two of them cost a bloody fortune, don't even ask .

(2) At the time I hadn't seen many actual testamonials from people who had the UT kit installed, so it was more of an unknown. Had I had more access to others' experiences, I would have been more open to it.

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

I just completely removed the servo and installed a 4-seasons manual heater valve....works well. however, i would like to completely replace the heating system with a manual one from a 240d...i think there is a complete write up on that conversion on here somewhere? as for the fan controls? i am in the same boat with only the defrost high working, it may be in connection with vacuum or the panel its self, i will be tinkering with it tomorrow, so, i will let you know if i figure anything out.

The climate control conversion thread is for a w123 chassis... the OP has a w116. Conversion isn't simple, I doubt that doing it between two different chassis is going to work.

Here is a later thread that includes links to several discussions:

http://www.peachparts.com/shopforum/diesel-discussion/326296-conversion-early-123-climate-control-later.html

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

I am sorry to read of your troubles with this car. I have always been able to keep the ACC II working properly. I am still using a Mantis Aluminum Servo that I bought from SSF in 2004 and it has given me no problems.

Have you been able to source an old plastic servo that has good internals???

I can't help with your bypass question, but I may be able to help you get the system working properly again...

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Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

My car has the aluminum servo. when I took the plastic cover off the top there was a lot of corrosion and the rubber vacuum lines were swollen due to heat. I thought about taking it out and see if I could clean it up so it functions or just chuck it and get the solid state unit. The valve doesn't leak, just doesn't move.....If I could figure out which vacuum lines operated which dampers I could go that route so I could at least have heat on the floor. The car has 105K miles, I'm the third owner. Car was given to the PO and it sat in his garage for 5 years so I'm assuming that's what did the servo in.... It was amazing that after sitting for 5 years I put in a new battery and it fired right up and idled smoothly...