It is possible that an overcharge will cause a leak in the piping system. Too much freon will increase the operatng pressures in both lines of your air conditioner system. Although it is not the only cause of increased pressure or leaking systems. A dirty condensor unit(the outdoor unit) is a much more common cause of high pressures that can cause leaks. The most common causes of leaks though are physical ones, something hitting your condensor, such as hail or basseballs. If the system is new, using soft solder instead of a brazing allow may cause leaks because the soft solder isn't strong enough to handle the increased pressure of the r-410a refrigerant that is replacing r-22.

Tipping allows the planner to know that you not only liked the job they did but appreciated it as well. Your planner should not expect to be tipped, however, and you should be leary if they ask for one.