99 Tahoe - AC Problem

I have a high-mileage 99 chevy Tahoe and I've determined (mostly due to loud clanking noises) that the A/C compressor has failed and needs to be replaced.
Ok, so I've removed the compressor as well as the accumulator, the front orifice tube, and the rear A/C unit expansion valve. I didn't see any debris in any of these places so I'm going to keep the existing condenser, evaporator, and tubing. This is an R134a system and the warning label on the accumulator says to be sure to add proper lubricant (i.e. PAG).
My service manual says:
"Determine the amount of oil remaining in the accumulator and add that amount."
In another place it says:
"Determine the amount of oil remaining in the compressor and add that amount."
Hmmm, confusing...
The problem is that there is no oil, at least none that I can find, in the accumulator or in the compressor. I do find "trace" amounts in that if I stick my finger in the accumulator there is a film of oil there as is to be expected.
So my question is HOW MUCH oil is to be added to this system prior to recharging with R134a? And where should it be added? One place in the service manual says add it to the compressor, another place says add it to the accumulator. Also, WHEN should it be added? Prior to evacuating the system or after evacuating but prior to adding the R134a?
I don't want to trash my new compressor before it even gets going...
Thanks, and any other tips on this particular system would be appreciated. BTW, this is the 4x4 4-door Tahoe w/ 5.7L V8. Has the rear A/C option as well.
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The PAG oil is added before evacuating the system. How much is determined by the total system oil capacity. Contact the place you bought the new compressor and ask what the compressor oil capacity is. They may also have the total system oil capacity. As to where it goes: some in the accumulator the rest in the compressor will equal the total system oil capacity. As an example: a system with the total oil capacity of 8oz=1.5oz in the accumulator/6.5oz in the compressor.
Be sure you use the correct PAG oil. There are differences. The compressor manufacturer will have the PAG oil specification.
Dave S(Texas)
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