Love this video ran into this issue on a phoenix rack the other day with oil issues and came to the conclusion that one of the compressors was blowing by into the crankcase. Valved off that compressor until we can get new plates and the oiling issues have seem to go away.
Hes talking about a pressure regulating valve thats connected from the discharge header into the interstage header on some racks. In case of multiple low side valve plate failures, and a subcooler thats off, the interstage pressure could fall so far that the compressors with no valve plate issues will see extremely low compression ratios on the low side. That will cause them to break reeds as well.
The ports you will typically use are the same ones the oil pressure switch uses, they should have a "T" with a Schrader valve. Dont use the one on the oil pump - thats gross oil pressure. The other is reading the body of the compressor (for any compressor). For Compound Cooling compressors, thats the "mid" pressure, or as Carlyle calls it, the Interstage. If you dont have that fitting, on the small bodies, use the one he showed, or one on the interstage line itself (on the compressor side of the shut off valve on the interstage). But if you have none of those, on the big body, its the Shrader valve directly above the oil pump.
