2000 Saturn LS2 ac repair

Not sure why all thats being replaced... Air shouldnt effect those things but humidity and dirt isnt good for your ac system. Your receiver/dehydrator assembly however will go bad if it is allowed to draw moisture. You should replace it if you havent already and it should be kept sealed (hook it up last on a dry day). All o-rings that you can replace should be replaced. They are a special nitrile o-rings. I'm not sure if the cheap kit from harbor freight will qualify as replacements.

----------- The receiver/dehydrator (R/D) is located to the left of the condenser and is mounted in a bracket which is welded to the condenser. Its purpose is to act as a reservoir for liquid R134a refrigerant received from the condenser. A constant flow of liquid refrigerant must be supplied to the TXV to allow it to regulate properly. The R/D assembly also contains a desiccant bag which absorbs any moisture that may have entered the system. The R/D assembly should be replaced any time it has been open to the atmosphere for an extended period of time as the desiccant will become saturated.

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Once everything is together a vacuum can be put on the system to remove all air and moisture from the system (except for what the desiccant absorbed). It can be left under vacuum to check for leaks as well. This is something I'm sure you're not equipped to do. Also the right type and amount of oil needs to be added. "Do Not" use mineral oil on the o-rings as it is a 134a system. For more information you can try