I siezed the AC compressor on my 560SL. I have a new compressor and receiver drier to install. But lately I have been reading many compressor overhaulers insist on flushing and replacement of the expansion valve. 18 years ago when I worked on these cars for a living I never heard of this and never did it. How important is this. It is a 1988 560SL with an Aluminum compressor R-12 system.

John Roncallo