I want to get my A/C system working well. The compressor leaks so I need to replace it. I've purchased a new accumulator/drier, orifice tube and compressor. I removed the old accumulator and orifice tube. The orifice tube has a lot of junk in it's screen and the accumulator is basically dry. I've put the new orifice tube in and the new accumulator. Do I need to flush the system and if so what's the best way to do this? If I do need to do I need to remove the new parts first? How much oil do I need to add to the accumulator? I've got a hand vacuum pump would that be good enough to pull a vacuum on the system and if so where would I attach it? The compressor is next what's the best way to take that out without damaging anything else? The new compressor says it was shipped without oil. How much oil do I need to add to it? What type of oil do I need to get? I'm going back R12 because I have quite a bit of it. How much R12 will I need to add after I get it buttoned back up?