Here's the troubleshooting info for the clutch coil, either read ohms or
amps depending on your test equipment.  This was copied from the MBCA
forums before they effectively killed it.  I met Bob Goodwin a few times,
retired Navy and a great guy.

"There is one thing that I don't believe is covered as well as it should be
and that is the clutch coil. Yes, the clutch coil. Famous for burning out,
shorting out or just frying a few windings. Not enough to blow the fuse but
plenty to disrupt the speed comparator and shut off the compressor
permanently or intermittently.

Of all the troubleshooting steps, checking the compressor clutch coil is
cheap and relatively easy. Measure current with a clamp on amp meter.
Reading should be 3.75 A hot or 4.2 A cold. Resistance should be approx 3.5
ohms hot or 3.1 ohms cold.

Everytime I chased an elusive A/C compressor problem in a Mercedes, it
turned out to be a bad clutch. I don't spend near as much on A/C parts

Robert Goodwin

Virginia Beach, Virginia
'87 300SDL
'95 E300D

Charleston SC

On Fri, Jul 17, 2015 at 11:45 AM, Max Dillon <> wrote:

> Wilton,
> I know that pulling the KLIMA relay will disable the AC compressor, that
> is located right behind the battery and fairly easy to get to, but may be
> pretty tight in the socket. A firm grip and gentle working while pulling up
> should free it. I don't know if a failing push-button unit would still blow
> the fuse if the KLIMA relay were removed.
> Pulling the plug on the top of the compressor would definitely isolate it,
> but that would also remove the compressor speed signal, which means the
> KLIMA relay would interrupt the power to the compressor clutch.
> A common cause of trouble in the AC compressor controls is a failing
> clutch that draws too much current. I'll have to search for a bit to find
> the normal amperage. I'd measure that current next if I were you, or is the
> test a resistance test? Need to start digging...
> --
> Max Dillon
> Charleston SC
> '87 300TD
> '95 E300
> On July 17, 2015 11:22:19 AM EDT, WILTON via Mercedes <
>> wrote:
>> Fan turns freely.
>> SWMBO took car out late yesterday with A/C OFF; everything else as usual.
>> Returned with fuse intact.
>> What is best way to isolate compressor from the system with controls calling
>> for cooling as usual?  Unplug wire on pressure switch at dryer?
>> What is the likelihood of a "glitche" in the control unit causing the fuse
>> to blow?
>> Same for temp. sensor motor?
>> Wilton
>> ----- Original Message -----
>> From: "Curly McLain via Mercedes" <>
>> To: "Mercedes Discussion List" <>
>> Cc: "Curly McLain" <>
>> Sent: Thursday, July 16, 2015 11:32 PM
>> Subject: Re: [MBZ] Blown fuse
>>  I'd check the engine fan to be sure it turns freely.  I think it is one of
>>> the highest energy consumers in that list
>>> I removed the fuse placard and carefully cleaned away the soot and
>>>> scorching as best I can.  I have deciphered the fuse #7 list to read:
>>>> backup lamp, heating water valve, water pump, engine fan, heating system
>>>> for washer jets, climate control system, relay aux fan term. 86, auto.
>>>> trans. electrics, blower motor inside temp. sensor, air cond. compressor.
>>>> (I filled in several obscured words with imagination and/or what I vaguely
>>>> remember.  Can somebody please verify it for me?)
>>>> Wilton
>>>> ----- Original Message ----- From: "WILTON via Mercedes"
>>>> <>
>>>> To: "Mercedes Discussion List" <>
>>>> Cc: "WILTON" <>
>>>> Sent: Thursday, July 16, 2015 1:39 PM
>>>> Subject: Re: [MBZ] Blown
>>>> fuse
>>>> #7 fuse has blown couple more times.  The placard inside the fuse box
>>>>> cover is scorched, obscuring the list of systems in addition to
>>>>> compressor on that fuse, and I can't open the pdf file showing such as I
>>>>> have many times before.  Can somebody, please, send me a photo of the
>>>>> placard or the appropriate pdf showing those items on fuse #7 for '87
>>>>> 300D?
>>>>> Wilton
>>>>> ----- Original Message ----- From: "WILTON via Mercedes"
>>>>> <>
>>>>> To: "mercedes list" <>
>>>>> Cc: "WILTON" <>
>>>>> Sent: Tuesday, July 14, 2015 4:51 PM
>>>>> Subject: [MBZ] Blown fuse
>>>>> SWMBO came in from short trip in the '87 300D,
>>>>>> leaned over back of chair
>>>>>> in cool living room where I was napping and announced, "Blown fuse in
>>>>>> the car.  I was driving along with air conditioning blasting away
>>>>>> nicely, and it just quit.  Don't ya think it's a blown fuse?"
>>>>>> I replied, "Yep; sure hope that's all it is."  'Hobbled out to car
>>>>>> thinking 30 amp blower fuse had blown.  Loosened the two mounting screws
>>>>>> thinking the fuse would fall apart as I removed it, but it did not.
>>>>>> Checked fuses in fuse box; 'found #7 (for compressor and coupla other
>>>>>> things) blown.  Because of my shaky hands, called SWMBO to help me put
>>>>>> blower fuse back in place and R&R #7.  A/C blowing ice cold again.
>>>>>> BTW, I did NOT change ALL the fuses.  ;<)
>>>>>> Wilton
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