Toyota Repair: 1991 Toyota a/c expansion valve and filter clogging, crank shaft, toyota camry

Question
I have a 1991 Toyota Camry LE Sedan, 160,000 miles, V-6 engine.  I would turn on the air and it would make a grinding noise. The air was not used once the sound was heard. Took it to repair shop and asked them to check and see if it was the a/c compressor.  I was told it was belts - they were cracked, I paid to have the belts replaced.  Two days later the sound returned when turning on the air.  Again, stopped using air & returned car to shop.  Was then told it was the a/c compressor.  An aftermarket compressor w/clutch was ordered (it was a few dollars less than the Toyota part and came with a new clutch - I was also told it was made by the same company that manufactures the Toyota compressor).  After the part came in, I was told that it wouldn't work with my particular vehicle (something about a "box" that was attached to my a/c compressor that wasn't included with the aftermarket - I'm still a bit confused about this bit of information#.  The Toyota compressor was ordered.  I was told the mechanic took apart my clutch to make sure it was in good working order - was told it looked great.  Few days later was told that the Toyota compressor didn't have the "box" on it either, so they were going with the aftermarket part with the new clutch anyway, and this way there would be a new clutch as well as a/c compressor.  Picked up the car after repairs were complete and within two start ups of the a/c, the original noise was back.  Returned to the shop again for them to look at it.  Finally told it was the crank shaft pulley. It was repaired, some money was returned to me for the difference in the unnecessary purchases/repairs.  Two weeks later the a/c blows very cold in the morning, then not at all.  Brought the car back and now I'm told it's the expansion valve and filter #dryer#.  Apparently it's clogged. I was also told by the repair shop that the current problem has nothing to do with the "repairs" to the a/c compressor.  I've done a bit of research and have been told that it is standard practice to flush the a/c system when changing out a/c compressors to avoid getting particles lodged in the expansion value due to the high pressure that occurs when the a/c is turned on. Is this true?  I would like have your opinion, if there have been enough facts provided, on this scenario.
Thank you,
NC Mom

Answer
You said "I've done a bit of research and have been told that it is standard practice to flush the a/c system when changing out a/c compressors to avoid getting particles lodged in the expansion value due to the high pressure that occurs when the a/c is turned on. Is this true?  I would like have your opinion, if there have been enough facts provided, on this scenario.

This is correct, when there is compressor failure there is a very good chance for metal shavings to get in the lines and cause clogging of the expansion valve and receiver drier and in extrme case can clog lines and the evaporator and condensor, yes, they should have recommended replacing both the valve and the reciever drier and checked the lines for metal shavings, by the way, don't accept the explanation that vacuuming the system removes these particles, this is false and a misconception, vacuuming only removes moisture in the system.