Time sensitive question, 97 tahoe W/O rear air

[FrankieZee]

First thank you in advance for any and all replys.
Ok so 97 Chevrolet tahoe 5.7 with out rear air.
What's new, everything except the compressor.
Including hi/low cut out switches and the control head unit.
I added <8oz of pag 150.
I added 36 oz of 134a.
When the compressor engages
Low side is at 49psi and kicks out at 22psi
Hi side 85 psi and kicks out at 65psi
Ambient temperature is 45 degs Farenheit.
Air is warm at the vent.
So time for a new compressor, thanks to Amazon I ordered friday night at 11:30 PM and had it delivered Sunday by noon.
So now the money questions.
How much oil to put in to the new compressor?
I really don't want to disassemble everything and flush.
My thinking the only oil in the system is what was in the old compressor and the <8oz. That I put in.
So drain the old compressor, take note of the volume and replace that amount back in the new compressor.
As to the time sensitively of the questions ? My only day off is tomorrow 10/29/18
Again thank you for any and all replys.

Frank Z.

[Cusser]

My thinking the only oil in the system is what was in the old compressor and the <8oz. That I put in.
So drain the old compressor, take note of the volume and replace that amount back in the new compressor.

If you really need a compressor, above should get you close, that's what most techs would do. Add some UV dye too when you do this, or add refrigeration oil that already contains the UV dye.

EDIT: see below

[GM Tech]

wtf--- 45 degree ambient and you say pump is bad......????? Of course it kicks out right away, there is nothing to do....pump will only run when system pressure exceeds 47 psi-- and your ambient is right on top of that. Switches are doing their job.. Your truck is not a refrigerator- don't expect cold air at ducts just because you turn on compressor-- your ambient is telling you that you don't need a/c- and compressor won't run hardly at all because of low system pressure due to that low ambient.....how well does it cool at 90 degf ambient? now that will be tell tale.....