A couple things come to my mind.
One: I have never seen a pressure relief valve built into a York compressor. I've seen them on the bottom of receiver/dryers, but not on the compressors. Even so, those relief valves are set for 400-600 PSI.
Two: You know the system has to be evacuated for at least 20 minutes to remove all the air before you charge it with refrigerant, right? A system containing refrigerant and air won't work. You need refrigerant only.
Three: 80-90 PSI on both the suction and discharge sides of the compressor is normal when the system is not running. The pressure of a non-running system is determined by the ambient temperature, not the charge level. A running system will be around 20 PSI on the suction side and 150 PSI on the discharge side, depending on a lot of things.
Four: The most accurate way to charge one of these systems is by watching the sight glass on the line between the receiver/dryer and the expansion valve. The glass needs to be clear (liquid only). Any bubbles mean the system is either low or contains air. These expansion valve systems are VERY tolerant on their charge level. Basically so long as there is enough refrigerant to maintain a constant flow of liquid to the expansion valve and not so much refrigerant that the receiver/dryer is completely full, then it will work perfectly. There is no "It cools slightly worse because it is low on charge" with these. They basically either cool to full capacity, or don't cool at all.
'72 Jeep Wagoneer Custom, 360 V8
I love how arguements end as soon as Ristow comments. Ristow is right...again.