That was my thought--that the compressor was seizing up and putting too much strain on the clutch.

The other reason I would tend to want to change the compressor too is that it seems like there is way too much chance of screwing up the clutch adjustment (for me) and a new compressor already comes with a clutch installed.

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles