Reason for low side filter:
What's the ONE component (where something could hide) that almost NEVER gets replaced after a compressor failure?

The evaporator. Even though the TXV will catch most debris; it's not like the orifice tube/accumulator systems which actually have a screen at the OT. I'd put on the screen that Delco makes for the R4 compressor inlet, with the history of your compressors. As components go,the condensors trap the most crud, true; but they can be changed. It's a loop system so you're right, high side filter is the most common, but low side filters (permanent or, often, temporary) are used.

Flush materials have many proponents/opponents, but the last flush needs to be really volatile. Safety, though.

HeCat is a great way to flush; For the DIY, Robinaire type gun is #2, air driven suction nozzle #3, pouring the flush in.. #4+.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)