OK, turns out it wasn't cleaning the contacts that made it work. The plug receptacle on the compressor is loose. If I push the connector down, it connects and compressor clutch engages. When I release it, it slowly vibrates upward until it loses connection and stops working. I guess I'll end up zip tying it to hold it down but I'd rather fix it properly if I can. Any suggestions? I think I'll be crawling underneath it tomorrow morning. I don't know how that plug receptacle connects to the clutch assembly but it looks like even if it were screwed in, I wouldn't be able to reach the screws without taking it apart, and based on what I have read online, I really don't want to take it apart. Thanks for your help.
Jim
--- In diesel_mercedes@yahoogroups.com, "n61cm" <jim@...> wrote:
>
> 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
> > >
> >
>
