Also, make sure to change the receiver dryer. Pull a long deep vacuum, and then check for vacuum leaks. No leaks, great, then pressurize the system with nitrogen, and once again check for leaks. No leaks under vacuum and pressure you will not be losing refrigerant over the winter. Having the proper tools is a must with air conditioning, and cleanliness is mandatory. I use latex gloves when doing A/C work, to keep my hands clean, and to make sure that no contaminates enter the system. Also, remember to lube all O rings before installing them, lube the threads of the hoses, and don't overtighten the hose nuts, which will almost always result in a torn O ring. Always use proper fitting wrenches and never use pliers.
