I left my advise at that because I really can't imagine how you would set the refrigerant level with gauges.
Pressures in A/C are the result of a multitude of factors. Too high of pressure running can be a number of things including poor air circulation. Too high of pressures at rest are due to the wrong refrigerant. The pressure of a system with some liquid in it will stay the same (at a given temperature) no matter the amount of liquid. The pressure being given by a temp/pressure chart.
Bosch Master, ASE Master, L1
33 years MB technician