FINALLY got the correct GM A6 compressor today. To recap: I bought a "modern replacement" on Ebay; turned out it would not work on the XJ 6 because bolts on the periphery of the compressor clutch will strike the tensioner bracket, so I sent it back and agreed to take a rebuilt A6.
Anyway, I have all new hoses, drier, new expansion valve, and a thoroughly flushed condenser and evaporator. I am installing R134A and need to know what kind of and how much oil to install along with the new compressor; also how much refrigerant you installed and what suction and discharge pressures you aimed for.
As usual, all advice will be gratefully considered! I am hoping to get the AC working before winter!

 

I would use Ester Based oil unless you can be sure that ALL the mineral oil is GONE.

The Ester will mix with the mineral and is supposed to be compatible with R134a.

The charge weight of R134a should be 80% of the R12.

Here is the info we got from Jaguar regarding this procedure.
TSB 82-39am

bob gauff

 

I consider all the old oil gone, as I removed all the hoses, the drier, and the expansion valve, then used compressed air to blow three cans of brake clean through the condenser and evaporator until it came out clear. Everything but the evaporator and condenser is new.
Thanks for the information!
RR

 

As quoted from the TSB........

"NOTE: The primary changes involve the replacement of the
existing compressor lubricating oil with an oil compatible with
both HFC R-134a refrigerant and with the residual R-12
lubricating oil. It is not possible to completely flush R-12 type
lubricating oil from the refrigerant system prior to changing to
Ester oil and R-134a. Additionally, it is necessary to replace the
input shaft seal of the Sanden compressor with a seal compatible
with the R-134a refrigerant and oil as described in the Technical
Guide. Harrison compressors do not require replacement of the
shaft seal."


You can flush the system but there will still be a tiny amount of mineral oil.

bob gauff

 

Several years ago GM issued guidance on converting R-12 systems to R134A, and their take was essentially that a small amount of remainder oil would not be a significant problem. There are opinions all over the map on this.
I am not trying to start an argument; just saying...