Hi folks. I have a 1996 C220 that seems to run perfectly except for a mild idle problem. At operating temp with the climate control sytem "on" the car will have a quick and small drop then return to normal in rpms accompanied by a faint "click" sound in the dash (like a relay would make) and a brief dimming of dash readouts. It does not surge above normal idle. If I turn off the climate control or if I switch on the "EC" mode, the problem seems to go away. I checked the overvoltage relay (000-540-67-45) fuse (fine) and cleaned the relay contacts and replaced it carefully so as not to push in the pin sockets. Should I just try a new relay ? I've read all the posts related to this topic. Is there a way to test the relay on this car? I saw other posts mentioning "pin 3" of the diagnostic socket, but the c220 diagnostic socket looks differently. I do have a fairly good multimeter (Hewlett-Packard), but without special auto features. Any suggestions?
The "Fast Lane" parts section of this website lists the "old" 000-540-52-45 relay, but the Parts Shop lists the new one (000-540-67-45)...I don't get it. Otherwise the car runs great...no hesitation, stalling, etc. I'd really appreciate any advice you can provide. Thanks in advance!