I just picked up a 77 300D with the Auto-climatic control unit.

I Know this has been discussed before and the solution most people go with is a rebuilt Servo, but how about using a this system instead? The A/C could still be used if the with a compressor switch. I just don't now how to control the dampers in the the system as well as the aux pump. At least the Defrost would work..


I think the system can control the fan speed and amount of water passing through.
http://www.jcwhitney.com/autoparts/ItemBrowse/c-10101/s-10101/p-100000150478/mediaCode-ZX/appId-100000150478/Pr-p_CATENTRY_ID:100000150478

If you have time to kill you can swap in the AC controls of a 77 240D with cable control of the flaps and thermostat... as God intended... just kidding, Larry

Sixto
95 S420
87 300SDL

Are you aware that there's a digital replacement for that servo available now. Performance sells them. It's pricey but probably worth the money if the rest of the car is in good condition.

__________________
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

If thats the 700 dollar unit then yep I saw it. Still just scratching my head about this thing. I only paid $650 bucks for it. I think my best bet is to use the George Murphy trouble shooting guide and maybe consider the rebuild unit on ebay for 285 less 65 for core = $225. She runs so good now that I fixed the broken TV rod. How involved is swaping out the controls from a 240D? any one got them for sale?
Thanks

www.**************.com

(Note, some have complained about Kent, I have always had good experience.

Early Automatic Climate Control Conversion Kit
Item # CMC-COMECC

On Special for the Month of August!

COMCKU - FITS THE FOLLOWING: 116, 107 and 123 Chassis For use to convert 1977 to 1980 automatic climate controls to a manual system. If your heat has failed again and you do not want to spend another $400 for a climate control servo maybe it is time to convert to a manual system. It will not be as nice as automatic, but at least you will have heat when you need it. This kit comes with a new manual control valve, hose section, splice fitting, four german hose clamps, and a 5 foot cable and complete instructions on how to properly install this kit yourself.

PLEASE READ CAREFULLY: If you are planning to make the climate control conversion to a manual valve, you need to understand a few things about the climate control servo system on these late 1970s Mercedes. As you are already aware, it is a very complex and often troublesome system. My kit is not a cure all, nor will it solve all the problems you could be having with your system. Converting it to a manual override will give you restored control of heat and cold. You will be able to turn the heat on in the winter and turn if off in the summer. You can regulate heat by partly closing the valve and using the different heater fan motor speeds. If you are using air conditioning then you will lose the automatic function of this as well. If your climate control panel is malfunctioning you may have to wire a separate switch directly to the AC compressor to turn it on and off. Since the AC with no longer cycle automatically the only way you can control the amount of cold air will be to cycle it on and off or to add heat to keep the temperature where you want it. If your system is plagued with vacuum leaks, then you may not even be able to get the lower fan speeds to work or the flap valves in the heater box to open and close properly. These are sometimes very difficult to find and repair and we are not able to lend assistance with these type of repairs. Our kit requires you to leave the servo in place with all its electrical and vacuum lines plugged in. This will allow continued usage of the blower fan at the lower fan speeds. Without proper vacuum supplied to the switch panel these two lower speeds will not work. The replacement valve is installed below the servo and hot water is routed through it instead of the servo. This will eliminate any coolant leaks you have been having through the case of the servo. The push-pull cable supplied with the kit can be routed inside the car near the dash, thus allowing you to adjust the valve for more or less heat while you are driving. Operation might seem a little crude, but you will not be stranded in the middle of winter without any heat as you may have experienced in the past. One more thing that is important. Just forward of the servo unit is a small electric water pump. This pump keeps coolant moving through the heater core when your car is idling. This keeps the temperature from dropping inside the car while you are waiting at a stop light. Make sure this pump is working. Unplug it and apply a 12 volt power source directly to see if it will run. If it is not working order a new one from us when you order this kit. It will allow you to control the heat better. For those of you who have had to pay the change the servo a few times only to have it fail again – I do feel your pain! SM6

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I "manualized" an '80 300D CC system a while back.
I controlled the vacuum modules for the air ducts with the existing vacuum valves, switching them on or off by applying +12v with a $1.50 toggle sw. Same type toggle switch is used to turn ac compressor clutch on. Heater core water is also on a sw.
Simple and, I bet I saved 30lbs in servo, vacuum lines and wire.

I hoped to document the procees someday but, its pretty obvious when you dig into the dash and see how everything works.

For us crazy folk who like to have somwhat of a plan in our head before taking things apart, please do consider doing this documentation about your conversion soon! It would make a GREAT addition to the DIY stickies. Besides.... what is obvious to one person is greek to another.

Thanks in advance

__________________
"If anyone knows other lessons I need to learn, please tell me. I'm tired of learning them the hard way".
by JerryBro

The Glow Plug Wait: This waiting period is a moment of silence to pay honor to Rudolph Diesel. The longer you own your diesel the more honor you will give him". by SD Blue

My normal daily life; either SNAFUed- Situation Normal... All Fouled Up, or FUBARed- Fouled Up Beyond All Repair

62 UNIMOG Camper w/617 Turbo, 85 300SD daily driver- both powered by blended UCO fuels

It not that I'm a Cheep A$$ but really.... Well maybe I am

The Vave is what $11.00 (http://www.rustrepair.com/STEPVAN_PARTS/onlinecat.htm?r=fr&p=WI-HEATER-HT.VAL)

Cable from Auto Zone $6.95

And how hard is it to add new heater hose at 50 cents a foot with a few hose clamps.

Just need to add a cable to to contol the flaps (dampers) to push air to the defrosters and or vents and floor.

Switch to supply 12V to both curulation pump and blower motor when turned on and another runs the AC compressor.