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 fr "Determ "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.

The oil circulates with the refrigerant when the system is operating. When the system is shut down, the oil settles in each of the components where it remains until the system is operated again. Each component has its own oil capacity. The only certain way to assure the correct oil capacity is to flush everything and start from scratch. The accumulator is not to be flushed, nor is the compressor, and since you are replacing these items, all you need to do is add the specified amount of oil to them before you install them (install the accumulator last). That leaves the front evaporator, the rear evaporator and the condenser. Each will have a recommended oil capacity, that capacity may be listed in the service manual under the specifications or it may be listed under the remove and replace instructions for those components. Oil is added at the time that the component is installed or re-connected back to the system. You will need new O-rings for each component that you disconnect when you flush. Do NOT lube the O-rings with PAG oil, use mineral (R-12 oil), PAG oil absorbs moisture and will cause the fittings to corrode. In order to prevent pulling your new fresh oil from the system when evacuating, you'll need to pull your vacuum from both the low side and the high side at the same time.