Well I can tell you with A/C systems, you will probably never see pressures on a sticker. The reason for that is Ambient Temperature, Barometric pressure, and even elevation can lead to different numbers being "normal". My leaf in Iowa would have different pressure numbers than a leaf in Texas as an example. There are average numbers for high/low pressures, but then again they are average. I've seen too many videos on A/C systems both home and auto and they both say the same thing. There is no "standard" high/low pressures.