The comfort level that the Oldsmobile A/C compressor provides for the passengers is now why this device is now standard equipment on all models from this car manufacturer. This is the mechanical device that compresses the refrigerant in your HVAC system that not only cools the air but reduces the amount of moisture in it. Today's A/C compressors are made to last, but will fail if the system is either not maintained properly or if an O-ring seal ruptures. The oil that lubricates this mechanical device on your Oldsmobile is suspended in the refrigerant that flows through it. If a leak occurs and only refrigerant is replaced, then the A/C compressor might not receive enough lubrication and begin to wear. The oil can also be restricted from entering the A/C compressor if the orifice or expansion valve is obstructed or becomes partially clogged. If oil is restricted to the Oldsmobile A/C compressor for an extended period of time it will begin to make a knocking sound. This is the interior pistons or scrolls beginning to wear, and their clearances are now out of their designed tolerance specifications. In some instances an injection of oil can resolve this problem if it has just begun. When this condition persists for a period of time, the A/C compressor will have to be replaced for it to function as designed. The Oldsmobile compressor also has a seal on the shaft where the clutch is attached to it. This is the seal that can rupture in time allowing refrigerant to leak out. If you have the right tools you can replace just the seal. If not the entire unit will have to be replaced for the Oldsmobile passenger compartment cooling system to operate properly.