Ok, 1981 300SD...Here in PHX it's a necessity to have the a/c working, and I've had a new compressor installed, new receiver-drier, the system vacuumed, cleaned, vacuumed again, and charged twice! (including two new compressors!!). After about 2 days the compressor starts clattering and clanging like I threw 2 rods through the engine! It still cools well, but at an idle it sounds so bad people look at me scared when I park next to them! Belts tight, bolts tight. Who knows what's happening? Like I said, this happened twice in a row. I might add that I'm set up on 134a, and a Nippondenso (I guess) compressor. Is there anything more modern/quiet/reliable to put on? These are what the Mercedes guys sold me, so I figured they would work best, but it's getting expensive to keep doing this. The compressors are warranteed, but the labor and a/c service adds up!...On a brighter note, this forum has been outstanding in helping me diagnose and solve the rest of my problems, thanks people!