You can manually change or control the flow of coolant, but the Evil Servo also operates the ducts openings and closings I believe. That is where it would get sticky......
Much info under "Evil Servo"

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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

when i attempted to unhook my servo at one time there were a lot of electrical demons jumping up. the car wouldnt turn over with it disconnected. i had a huge draw from it at one point as well. when i plugged the electrical back in, all was fine.

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1980 300D

yep, on the top rear side of the servo there is a gang connector of vacuum lines, they are linked to vents and stuff in the cabin. It's best to leave those connected to the servo, even it is not controlling coolant.

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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

Performance Products has a Digital AC Servo Upgrade Kit for $600.
http://www.performanceproducts4benz.com/productpage.aspx?pid=109850&cid=3&sid=383

[IMG]http://content.************************/main/109850/NO.jpg[/IMG]

I put the digital replacement listed above in my 77 300D last year, have been totally pleased. A little pricey, but we bought the car new and will always have it, so well worth the money.

Ron

Yes, you really can't operate the vacuum pods under the dash without the servo in place. The bypass system is good to solve a cracked servo with leaking coolant but functional otherwise. Without the electric/vac portion of the servo working, you're going to be stuck with the defrost default. You could manually wedge open the footwell vents and get heat to your feet, that would seem to be the simplest solution without replacing your servo if it is not leaking and you are actually getting heat. But I don't think you'll get much temperature regulation, just full heat in the defrost mode plus heat on your feet with the vents wedged open.
Cheapest solution is to look for a used one at the pick and pull. Best solution is either a rebuilt aluminum bodied one or the computerized replacement. Or, move to Florida.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I did this modification a few years ago after chasing gremlins constatly on my 1980 300SD. Also, I couldn't see $600 or so for an electronic servo that may ormay not solve the heating.

I took out the servo entirely and replaced it with a bypass valve activated by a push/pull knob that I ran to underneath the steering wheel through the firewall. The fan control I think I ran to the vacuum connection in back of the dash and the fan speed is controled by the dash buttons. The only issue is because of the vacuum control the fan will always run on at least low.

The A/C i connected to an additional fuse block controlled by an on/off switch installed again below the steering wheel in the dash. The normal dash switches control the fan speed.

When you want A/C turn on the switch and set the fan setting to the level you want and you got cold air. When you want heat you use the push/pull know to control the amount of heat and also set the fan to the level you want.

It is not as elegant as the original but for about $50 - $75 it works and I'm not concerned with any vacuum or electrical issues popping up.

I also did the same thing with the glow plugs: push a button to turn them on, hold the button in for as long as you want them on then start the engine.

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Rev. Dr. G. Church of the SubGenius
It doesn't take a genius

Is this still available?

I think I could come up with a simpler, cheaper solution if there's enough interest.

Unwired tools has the same type up grade. I think it use to be listed for
$700.00 and could buy it direct from them. now they don`t sell to the
general public.

www.unwiredtools.com click on the buy tab, then click on ssautoparts.

then click on ACC II installation manual. seems easy enough to DIY.

looks similar to the performance products picture.

charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

http://unwiredtools.com/accii.asp

Yes, it looks almost identical.