A friend's '98 C230, 44K miles, recently lost the A/C compressor... the unit briefly made a clunking noise when engaged... shortly afterwards, the noise stopped, as did all cooling. The clutch continues to engage when activated and the pulley turns smoothly but the compressor is quiet and high side and low side pressures remain identical.

The local dealer says they've begun to see elevated failure rates for these compressors.

What happened here? M-B offers a reman'ed unit but this is not a cheap unit to replace. Thought the variable displacement compressors were more reliable than the previous generation of NDs.