The best advice
I can give you is do not connect or allow anyone to connect gauges to that system. The CU100 does not fit to the old style designs that leaked. The line connectors will not leak if torqued properly when installed as they do not rely on Oring seals
The CU100 contains less than 120 grams of clean moisture free refrigerant. Your gauge set can easily contaminate your refrigerant. To confirm now that refrigerant charge is correct operate unit for a day and record
in log the places where frost is present. Then later when you suspect loss of refrigerant compare frost formations. Also if you keep the fan cooled condenser free of hair and dust and and check running amperage to be normal you will avoid mistakes
made by others. Amperage will vary if compressor
speed is changed or if major changes occur in ambient temperature.
Refrigerant servicing on your unit is with only the fitting attached to compressor
dome. Removing this cap may damage the seal inside cap then you will loose refrigerant again.
Any time refrigerant is lost
on a will designed system it will leak again if leak is not found and corrected.