There are many types of compresor failure. The most common is also the simplest to fix. That is a leaking compressor. The system functions but it can't keep the refrigerant in.
The most devastating of all AC failures are the mechanical destruction of NipponDenso compressors. The fallout from the destruction forms all kinds of contaminants; the worse of which is a condition nicknamed "the black death". Search the archives.
The black death happens in Nippondenso compressors because instead of using rings for piston seals they use teflon coated pistons. In the caldren that occurs during failure, compounds of teflon, carbon, oil, aluminum, whatever are created that are carried throughout the system. While it is concievable that the low side components of such a system might be flushed, the problem occurs on the high side where even after the most abrasive of flushing, a coating remains that is instantly released once the high side is running at temperature once more.
So, I have been using a combination of MB and Denso rebuilt this year. The Densos are a new product this year and look real good. On the box they describe what they do in rebuilding, and I assume they are at the state of the art on their own compressors (one would think that the original manufacturer would do the best rebuilding job) but they state clearly that they reuse pistons after careful testing. They DO NOT restore the teflon layer they only check to see it hasn't failed.
Probably the worse thing I see happen to 300Es is the replacement of a compressor for leaks and loose the whole system to a rebuilt meltdown. Believe me we learned the hard way when we first started fixing Nippondenso failures over 15 years ago. After some of the worse repair disasters I have seen in business we only used new compressors or ones we resealed ourselves for a number of years until MB came out with their rebuilts. WE have used MB rebuilt, Porsche rebuilt, and VW rebuilt Nippondenso compressors and only MB have given good service. Luckily all the defects have been leakers so far, nothing like the failures of the aftermarket rebuilts we used in those early days more than ten years ago.
Bosch Master, ASE Master, L1
33 years MB technician