and anytime a system is left open for much duration, the ENTIRE system should be flushed, and PRESSURE tested, not vacuum tested!!!
also, since it's impossible to properly flush a compressor, I recommend replacing it as well.
you CAN push fresh clean oil through a compressor by carefully filling the suction line, and turning the crank BY HAND SLOWLY until all the oil is pushed out of the compressor. it's usually better in the long run to just replace the compressor.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!