[diesel_mercedes] FIXED IT !!! Re: Troubleshooting A/C - W123 1984 240D

 

So a few minutes ago I pulled the wire plug from the side of the compressor and checked the voltage, which was over 12 volts when key turned to second notch (engine not started) and interior A/C control switch set to MAX. Then when I turned off the A/C control switch, key still ON, voltage went to 0. That's the way it is supposed to work AFAIK. However - the contacts looked really dirty...

Next, I checked the gap on the clutch. It is a bit oversized I think, at .035. That didn't look good. But darnit, should be close enough, right?

So I sprayed the contacts with Johnsen's electronic cleaner (I'm almost out of that, remind me to get more). Then I scraped the crud off them with a dental pick.

Reinstalled wire plug to compressor.

Freakin' thing WORKS.

So that's the A/C Tutorial for the day LOL.

Jim

--- In diesel_mercedes@yahoogroups.com, "Nate" <vwnate1@...> wrote:
>
>
> So far so good ;
>
> I'm not really familiar with the basic factory AC in our '82 240D but I assume there's a relay in there some where , if it goes bad you'll get just this symptom so if no power (of conversely , power but no ground at one leg of the MPC) to the compressor connection , I'd go looking for the AC relay .
>
> Yes , you can change the clutch complete on the R4 compressor , back when your car was new it was a really common repair , I had to do many as well as the ceramic compressor seal that failed a lot .
>
> Requires a special tool I assume is cheap or loanable from your FLAPS .
> Mind the threads as you turn the tool into the clutch ! if they're damaged they can ruin the inside threads causing you a peck of extra work and $ when you replace the whole compressor .
>
> -Nate
> Jim wrote :
> >
> > Troubleshooting A/C - W123 1984 240D
> >
> > Symptoms:
> > - compressor clutch will not engage
> > - blower fan works fine
> > - no blown fuses
> > - freon pressure good
> > - pressure sender switch is ON
> > - external condenser fan works fine
> >
> > What I have done so far:
> > - checked freon pressure - good
> > - jumped pressure switch wires - nothing
> > - checked pressure switch resistance - switch is ON
> > - turned the controller switches inside the car on an off multiple times - nothing
> > - turned the temp wheel from OFF to MAX multiple times - nothing
> >
> > What I figure I have to do now:
> > Check and see if voltage is getting to compressor clutch
> >
> > If yes - then clutch must be the problem
> > If no - then it's probably in the controller or mystery box, or less likely, wiring
> >
> > Does this sound like I'm going in the right direction?
> >
> > Also, if it turns out to be the compressor clutch, can I swap that out separately or do I have to put a whole new compressor on it?
> >
> > Thanks y'all,
> >
> > Jim
> >
>

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