Can anyone explain the difference between the two different Climate Servos? I've been noticing a 102 and a 104 sticker stamped on the sides of these. (see pics).

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To the best of knowledge they are the same part. I have a old Chry Imperial book that I use for reference when working on my 123.
Sure wish I could get my hands on one of those servos for a good price

__________________
"Any sufficiently advanced technology is indistinguishable from magic"
-Arthur C. Clarke

"I won't be wronged. I won't be insulted. I won't be laid a hand on. I don't do these things to other people. I require the same from them."
--John Wayne.

OBK member#16
77 300D
75 300D (rusty parts car)
73 220D (Dad's)
98 Jeep Grand Cherokee
82 Kawasaki M1

I saw two brand new servos for sale on ebay, each for a different model of car. Notice the 2 different part numbers...

1.) Bid is for one NEW, never installed, Delco #15-5307 (Mercedes #000-830-06-84) Air Conditioning Climate Control Servo. Found in a closed dealership, listed as fitting:

• 1978 1979 1980 Mercedes 300SD
• 1980 1981 Mercedes 380 SEL
• 1980 1982 380SL, 380 SEL
• 1980 1981 Mercedes 300TDT
• 1981 1982 380 380SEL

2.)Bid is for one NEW, never installed, Delco #15-5306 (Mercedes #000-830-03-84) Air Conditioning Climate Control Servo
Found in a closed dealership, listed as fitting:

• 1979 1980 Mercedes 300TD
• 1976 1977 1978 1979 1980 1981 Mercedes 280E
• 1977 1978 1979 1980 1981 Mercedes 280CE
• 1980 1981 Mercedes 300TDT
• 1976 1977 1978 1979 1980 1981 1982 Mercedes 240D, 300D
• 1977 1978 1979 1980 1981 1982 Mercedes 300CD

These applications are from the Delco Parts Catalog, the Mercedes number above is provided to help identify any other possible applications that are not listed here.

I just put in an aluminum model but the problem I'm having is the heat will come on when the car is cold but after about 10 minutes it will start to blow cold air, even with the temp dial set to 85. Plenty of heat regardless on defrost. Just wondering if I have the wrong servo in my 300D.

I don't know about the three-digit stickers, but I have pulled apart several servos now with two different part numbers, (Not the three-digit number.) They are functionally the same with only slight internal differences. I've also noted that rubber bits vary in colour, and possibly compound within them.

If it's an ACCII, it'll fit anything else with an ACCII. Again, they're all functionally the same. (When they function!) I could pull one off on an old Imperial and bolt it right up to my Merc.

__________________
- K.C.Adams

'77 300D Euro Delivery
OM617 turbo / 4-speed swap
404 Milanbraun Metallic / 134 Dattel MB-Tex

Current status:
* Undergoing body work

My '77 300D progress thread

I don't think it's servo issue. I would be looking at vac and wiring. Most likely vac

copied from a newsgroup: Hope this helps !!! This Info worked for me.

First, the dash does not need to be removed to get to the temperature
control resistor. Your problem is not likely the temperature wheel.
Follow the steps below. The parts for this system are too expensive to
throw parts at it.

The temperature is sensed/controlled by a sensor chain. The sensor
chain consists of a series of resisters; the ambient air temperature
sensor (located on the firewall just behind the engine), the
temperature dial, the in-car temperature sensor (for the 107 chassis
the in-dash sensor is located in the center of the dash) and the
resister in the servo.

The first step in checking the servo is to verify the resister chain
and amplifier.

To check out the resister chain,
1. Remove the ACC amplifier (located to the right of the glove box)
and connect a ground to pin 3 of the connector plug.

2. At the servo electrical connector, connect an OHM meter between
pins 1 and pin 2 on the left of the connector.

3. Place the temperature wheel at max (85 degrees) and the resistance
should be between 2.2K ohms, and 4.7K ohms.

4. Place the temperature wheel at 65 degrees, and the resistance
should be between 1K ohm and 3.5 K ohms.

When you finish, re-install the amplifier.

If the circuit is open at any place in the resistor chain, the result
is heat. If the chain is OK, then the problem might be the amp.

To check the amplifier, connect a voltmeter between pins 1 and 7. With
the ignition switch in the on position, the voltage should be about a
volt. Move the temperature wheel from cold to hot. The voltage should
increase to about 5 volts, and when the servo finds it home, the
voltage will drop back to about a volt. If it does not vary, then the
amp is bad.

The servo (usually big black contraption under the hood) responds to
the temperature control resister chain. It has a small electric motor
that routes vacuum to control flaps, moves variable resister to send a
signal to the amplifier, and opens and closes the hot water valve.

The motor in the servo receives a voltage signal from the amplifier
that is located behind the glove box. If you want to test the servo
motor, remove the vacuum lines and the 10 pin electrical connector.

Pin one is on the right of the connector looking at the servo.
Connect a ground to pin 1 and +12 volts to pin 5. The motor should
run.
Reverse the wire and the motor runs in the other direction.
If the motor does not run (you can hear it), the servo is bad.

You might also have a shorted aux water pump. This electric pump is
located just in front of the servo. Disconnect the pump and connect it

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__________________
"Any sufficiently advanced technology is indistinguishable from magic"
-Arthur C. Clarke

"I won't be wronged. I won't be insulted. I won't be laid a hand on. I don't do these things to other people. I require the same from them."
--John Wayne.

OBK member#16
77 300D
75 300D (rusty parts car)
73 220D (Dad's)
98 Jeep Grand Cherokee
82 Kawasaki M1

Absolutely beautiful "short version" of how to check basics on the ACCII - I need this info right now and am glad to find it. Maybe a mod can put this as a sticky somewhere?

Glad to be of some help... can't tell you how many hrs I spent searching down that info.
Hope it works for you.

__________________
"Any sufficiently advanced technology is indistinguishable from magic"
-Arthur C. Clarke

"I won't be wronged. I won't be insulted. I won't be laid a hand on. I don't do these things to other people. I require the same from them."
--John Wayne.

OBK member#16
77 300D
75 300D (rusty parts car)
73 220D (Dad's)
98 Jeep Grand Cherokee
82 Kawasaki M1

The difference between the -0684 and the -0384 servo is only the value of the resistance in the feedback potentiometer. You can safely use either one. If your car had an -0684 servo and you replace it with a 0384 you should adjust the thumbwheel to a resistance of 300 ohms at 65F, it's probably around 500.

BTW, the sensor chain is much easier to check using the test connector. The test connector is the rectangular pin-socket connector with 12 positions, 9 of which are populated. I'll update this thread with a link to the diagram which includes the test connector, it's too big to upload directly.

Having never successfully pulled but two working feedback pots, both from identical units, I would never have known this. Good info. Thank you for posting it.

__________________
- K.C.Adams

'77 300D Euro Delivery
OM617 turbo / 4-speed swap
404 Milanbraun Metallic / 134 Dattel MB-Tex

Current status:
* Undergoing body work

My '77 300D progress thread

if my memory serves correctly one servo was for gas cars and one for diesel due to the inherant problems of getting enough heat out of a well running diesel.

__________________
David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
http://www.w108.org/gallery/albums/A...1159.thumb.jpg

I did have a 104 servo and now have a working 102 servo, so I readjusted the thumbwheel and now it works great.

It does take a while for the car to warm up enough to produce heat though.

Hello!

I have 102 servo unit/valve from 1981 380 SLC.

Can anyone please tell me the resistance of the feedback restistor when servo unit is in park (or full heating, full cooling) position ?

Thank You!

Also, how do you re-adjust the thumbwheel? I went from a 104 servo to a 102 and the wheel needs adjustment.

__________________
1980 240d
1999 SL500

When the outside air temp, the inside cabin air temp, and the thumbwheel setting are all the same then the resistance of all 3 should total about 3300 ohms. It's much easier to measure all 3 together because all you have to do is probe with your ohm meter between pins 2 of the servo electrical connector and pin 3 of the servo amplifier connector.

The job of the servo amp is to drive the servo so that the potentiometer inside the servo equals the sensor chain resistance.

You can also verify these components individually by taking apart the test connector and probing there. PM me for a chart of the resistance of the thumwheel and temp sensors.

If you don't have service manual CD you can freely download the instructions for our thumbwheel rebuild kit from www.unwiredtools.com . The adjustment procedure is there. You don't have to take the thumbwheel apart. Just hold the potentiometer shaft with a small tool while you turn the thumbwheel. It's a 5-minute job.

When the servo is parked the value of the feedback pot should be between 1300 and 1500 Ohms.

__________________
Steve S
Support Tech
UnwiredTools, LLC
www.unwiredtools.com

1982 380SLC
1994 E320TE
1998 E300DT

UT_Tech: Thank You!