Thanks so much for your reply. Finally somebody replied!!

Well, the reason why the relays were missing were that this car came from an auction and you know how it is, when a car is at the auction, people steal stuff from emm either for their use or so that the vehicle does not sell at a good price!!!

The vehicle was hit on the left fender, it damaged the spindle. both the fender and spindle were changed.

The OVP is brand new from Merc. The refrigrant compressor cutoff relaye (next to OVP) was bought as a used one. But it also came from a 87 300D. The problem is, the A/C goes on automatically when the car starts but it blow hot air, not really hot but not cold either, and when I change it to hot, it does not blow any hotter air! We check for freon and added some 134 to the R12, so freon is good. But you see the pully on the compressor does not run. How would you suggest I trouble shoot and track the problem??

About the intermittant working of Tacho and ABS light, this only comes on when either the car is cold on the morning just after I start, it might hicup a couple of times when the Tacho works for a few seconds and the ABS goes off!! but then through out the day, it does not work unless if I go over a pot hole, not surprissingly, it only happens when the left wheel goes in a pothole not the right??!!! the same one that was hit.

BTW, is it safe for me to drive the car when the RPM does not work and the ABS light?? I dont mean ABS wise, I mean engine wise. coz the engine idles a lill better when the ABS goes off and the tacho works!!

My main problem right now is to trouble shoot the air conditioning system, boy its hot in Houston!! I took it to this Merc guy and he said the compressor needs to be checked?? that kinda does not make sense, keeping in mind the car has only 96k miles ORIGINAL.

Oh boy, this is a long posting!!!

Would appreciate your comments.

Thanks
Mehdi