If you charged to a clear sight glass, the amount of charge or compressor is probably not your problem. I would look toward a vent door opening to outside air, or some other ducting control problem.

The compressor typically pumps okay or it doesn't. If the compressor is pumping, it's not something that will cause your problem. Your low side pressure will typically be around 30PSI with a good charge. The high side will vary, but could be around 190 to 250PSI.

Good luck,