I'm not sure what compressor you have but you can certainly buy just the bearings. Almost any AC shop can sell em to you, any part of the clutch , compressor shaft seals and gaskets too. The trick is getting the clutch off. Typically the outer clutch plate is held on place with a nut which you need to spin off with an air wrench, or a hand wrench if you can hold it from turning. Then you may need a special tool that threads into the outer (driven)clutch and pushes against the compressor shaft- off comes the outer clutch. The pulley contains the bearings and is held on with a snap ring. You then need a puller and hub that goes over the end of the compressor snout to weasle the pulley off. Sometime they just slide off- it depends on the make of compressor. If it's a Chryslerized Nippondenso it might just all come apart easily. Never with a GM compressor.But you may need $150 in special tools to do it and you may not.When you get the outer clutch off there may be spacer washers in behind it, don't lose them. The gap between the pulley and the driven clutch is important. At all times be very careful not to damage the shaft seal which is located at the bottom of the snout of the compressor.