I am not sure what is done with the system off and the system on. Obviously, pressure testing and deep vacuum is done with system off. Should system still be off when you open the pre-charge valves and weigh in the additional refrigerant required for the additional line set length?
I know system has to be on to check the pressure but if some additional refrigerant is needed do you do it with system on or off? I appreciate anyone's help on this.