Wilton, It's certainly closer to anything I have seen so far.
What I recall is that the MAS only had four populated sockets (pins) in the relay socket, which is why I'm confused by the depiction of at least seven connections. I won't get to see the car again until tomorrow morning, but I'll verify what I have against the drawing you sent. At least that way I might be able to do some voltage and continuity checks to narrow things down. Thanks! Dan On Mar 14, 2012, at 8:14 PM, WILTON wrote: > Dan, > > 'Just set you a comp. clutch schematic. Is it the one you need? > > Wilton > > ----- Original Message ----- From: "Dan Penoff" <lwb...@yahoo.com> > To: "Mercedes Discussion List" <mercedes@okiebenz.com> > Sent: Wednesday, March 14, 2012 7:00 PM > Subject: Re: [MBZ] 300 ACC Issue > > >> I have found a reference to the MAS and what it does in the AC manual, but >> they use that darned breakout box to do the troubleshooting. >> >> If I could find a schematic I could figure this out in short order, but the >> ones I have been looking at are for older models that use the KLIMA relay >> and not the MAS. >> >> Dan >> >> >> On Mar 14, 2012, at 6:05 PM, Dieselhead wrote: >> >>> Read #2 and #3 here >>> http://www.w124performance.com/service/W126/Index/Misc.htm >>> >>> I think you are right, that the wire from the low pressure switch to the >>> comp is the clutch power wire. With it off at the comp, measure resistance >>> of the terminal on the compressor to ground. Open or near 0 resistance >>> means the coil is bad. (obviously) I don't know what the resistance should >>> be, probably 1.5 to 3 ohms. is a good coil. >>> >>> You could also have someone turn on the AC while you are measuring the >>> voltage of that wire to ground. It should show 12v for a short time, until >>> the system detects the pulley is not turning. >>> >>> It is possible the "everything" relay replaced the Klima. Or maybe they >>> moved the Klima on that model. >>> >>> >>>> OK, guys, pile on. I'm in unfamiliar territory here, and could really use >>>> some direction: >>>> >>>> 1992 300E 2.6, complaint is AC compressor won't come on. >>>> >>>> Original complaint was that the #7 fuse was blowing, killing all ACC >>>> related functions. Fuse was replaced, and now ACC functions as expected, >>>> that is, fan speeds, doors, heat/defrost, etc. Everything works but the >>>> AC compressor. >>>> >>>> I shorted out the low pressure switch with no result. Checked for power >>>> in the harness to the low pressure switch in reference to ground and got >>>> nothing. >>>> >>>> This model has a MAS relay which may or may not play a part in this, but I >>>> don't have a schematic, so if anyone does, I would really appreciate you >>>> forwarding a copy to me, as that would make my life significantly easier >>>> in identifying the problem. >>>> >>>> If I pull the MAS relay while the car is running the engine dies, as I >>>> would expect. Since it's supposed to interface with all sorts of things >>>> like the fuel pump and other goodies, it appears to be working as >>>> intended, as everything else on the car works perfectly. >>>> >>>> I have to believe there is a failure in getting a signal to the compressor >>>> clutch, but without a diagram I'm swinging in the proverbial wind. I >>>> would put B+ to the clutch, but I'm unsure of what wire is which, and I >>>> don't want to smoke the speed sensor in the process. >>>> >>>> From what I can glean, it appears that power comes in, goes through the >>>> low pressure switch, and then on to the compressor clutch. That's an >>>> educated guess based on what I am seeing, but I'm not tearing harnesses >>>> apart, either. There are three wires going to a connector on the top of >>>> the compressor, two of which go off in a separate harness that heads up >>>> under the air cleaner. The remaining wire goes to one side of the low >>>> pressure switch. I am assuming the two that head into the engine harness >>>> are for the speed sensor. >>>> >>>> Dan >>>> _______________________________________ >>>> http://www.okiebenz.com >>>> For new and used parts go to www.okiebenz.com >>>> To search list archives http://www.okiebenz.com/archive/ >>>> >>>> To Unsubscribe or change delivery options go to: >>>> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com >>> >>> >>> _______________________________________ >>> http://www.okiebenz.com >>> For new and used parts go to www.okiebenz.com >>> To search list archives http://www.okiebenz.com/archive/ >>> >>> To Unsubscribe or change delivery options go to: >>> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com >> >> >> _______________________________________ >> http://www.okiebenz.com >> For new and used parts go to www.okiebenz.com >> To search list archives http://www.okiebenz.com/archive/ >> >> To Unsubscribe or change delivery options go to: >> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > > > _______________________________________ > http://www.okiebenz.com > For new and used parts go to www.okiebenz.com > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
