Hello all,
I've got an '80 300D still set up for R12. 2 years ago I charged it up and had wonderful AC for about a week or two. This was my first foray into AC work and I clearly should have done more homework.

So what I have is a system with a significant leak (or leaks). I've spent the last two weekends reading through forum posts new and old (with this one being the most informative; which is why I'm resurrecting it). Surprisingly there are few/no clear step by step's that I've seen and requests for confirmation of steps (e.g. #25 in this thread) often go unanswered. So I'd like to propose my plan of action and ask for thoughts:

1. My system 'works' but leaks based on previous experience.
2. I've just replaced all O-Rings and will replace the seals from manifold to compressor (original R4 sytle) this afternoon.
QUESTIONS:

• Should I drop the compressor to replace the seals, or leave in place and keep oil in it?

• If I drop the compressor, should I drain the oil?

3. Adding a new dryer to the system
QUESTIONS:

• I know I need to keep moisture out of the dryer once installed. Do I immediately go straight to my Nitrogen pressure test and then pull a vacuum to remove the moisture and prepare for charge?
  Under the scenario of not dropping the compressor and adding a new dryer, should I add any oil to the system? My compressor looks pretty gnarly, but not sure if that oil is from the compressor (thus my levels may be low) or the recently repaired vac pump.

• I have some R12 Oil Charge (see photo [assuming links work]). If I should add oil based on above, should I use this and does it count towards my R12 charge, or only oil volume?

Once system passes pressure test (150-200 psi for an hour or few; seem to be lots of varying suggestions here) I then vacuum down and charge using the R12 cans I have (images below) following the volume specified on the car.

Also, the link to the recommended pressures in the OP of this thread is dead. Anyone have an updated link or care to confirm these numbers for me?

Image of R12 Oil Charge
Image of R12 cans