Evil Servo is dead!
 

the Climate servo on my '81 is toast, it only blows air in defrost mode. is there a way to bypass the system or possibly swap in a manual system from a different year? i have heard that some folks install a petcock with a manual choke cable to solve the problem? any insight on this issue would be appreciated.

Answer
 

I hope this helps. :)

Evil Servo service manual
Evil Servo, service manual - PeachParts Mercedes ShopForum

Evil Servo bypass
http://www.peachparts.com/shopforum/diesel-discussion/286770-evil-servo-bypass.html#post2567364

Maybe pictures will help. Trying to get my heater working. Where to start?
http://www.peachparts.com/shopforum/diesel-discussion/238588-maybe-pictures-will-help-trying-get-my-heater-working-where-start.html#post2029228


Unless you are talking about the push button control unit.

http://www.peachparts.com/Wikka/W123ClimateControl

http://www.peachparts.com/shopforum/diy-links-parts-category/142408-climate-control.html



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i thought servo was up to 1980 cars.

Nope, it is in the '81's too...unfortunately. i think they omitted the automatic climate control servo in 1982? it is funny that the only part of the car engineered by Americans is a total chunk of *****!
Any who, i have heard of folks doing a complete conversion and taking out the old system and replacing it with a heating system from a later model 123 body style. there is also the plumping valve option as well, however, i have not seen any examples of either fore mentioned methods? i think the plumping valve would be my choice...love having the ghetto in my rigs.

81 what? The W126 had the non servo Behr system from the start (1979). I thought the W123 had gotten the W126 system by 1981.

-J

Here is a post on the Wiki where someone removed the manual climate control system from a 240D and swapped it in for the servo system.

PeachPartsWiki: Auto to Manual Climate Control Conversion

Looks somewhat involved but if done right looks and works stock.

1980 was the last year for the ACCII system. Are you sure you have a servo?

1981 had the more modern unit with monovalve.

Only blowing air on DEF sounds like a vacuum leak, how did you determined the servo was bad?

oh, i am positive it has/is the servo, i have had to replace many of them! it is not cheap, so, at this point i would rather omit the system and have manual controls. this rig has been going through a simplification process for the last five months. it would be nice to get rid of the servo altogether, i figure the more faulty components i delete, the more reliable of a field rig it will become. which that is my main goal for the wagon. i will photograph the servo and post it tomorrow morning.

Gavin Leslie mentions it would be simpler to replace the whole unit, than source the bits as he did in the above thread.
I have talked to him a few times eye ball to eye ball.

Here is a link from Bruce Kennedy, swapping in a 240D Type 1 system into his 83 300TD.

http://www.peachparts.com/shopforum/diesel-discussion/187373-climate-control-manual-conversion.html

He mentioned here the 1980 240D was the best yr to pull one from.

http://www.peachparts.com/shopforum/diesel-discussion/211899-climate-control-conversion-editorial-coming-near-future.html


I have pulled 4 of these units from 240`s, not really all that difficult to do. you will have to remove the dash. I remove the steering wheel just to give me more room to work. practice at PNP, and remove things as if you are working on Your car. take pictures and document things as you remove them. use some masking tape to lable what wires went where etc...

I have one I took apart to clean and replace the foam on the doors. cleaned out the 30yrs of dirt from the box and Evaperator fins and checked over the Heater core. that is as far as I got then got side tracked to another project. take picture as you go on this one too, there are just a bunch of clips and 3 sections to the box.

Charlie

Nice write up, I am going to try this on my 124, should be similar?

I replaced my 77 with the electronic box, a little pricey, but we are keeping the car. It works fine and keeps the rest of the controls working like they should.
You would think after MB messed with Chrysler on this they would have had enough sense not to buy them and make them profitable.
ron

I am heading to a yard around Corvallis tomorrow to check out a possible parts car for the entire climate system. So, nobody has heard or tried the bypass method using a manual choke and plumbing petcock? That sounds the easiest?