The system has to me analyzed by a knowledgeable refrigeration tech. A/C is not something that you will learn online. The first step would be to have an complete evacuation and recharge done to get the exact amount of refrigerant required for that system. Too much is a problem and too little is a problem. Have them install some U/V dye in the charging process so if there is a leak in the system, it can be found easily later.