Hello . If you noticce it lost too much oil, when in doubt, you can replace it by taking off what's left and adding new oil.You don't have to change anything else, but you do have to make a good cleaning to the system with 141b cleaner agent and nitrogen barrides. Clean well the expansion cage and the evaporator, it usually logs a lot of garbage in the cars and they get blocked; merming the perfomanceDon't leave anything doubtful or without cleaning, because afterwards, if it doesn't perform okay, you'll have doubts about where the cause can be