Hi, if its just the bearing on the pulley then it is really easy to replace yourself. I had to do this a few months back.
1.Take the pulley off the compressor (If you need more help on how to do this just ask).
2. Measure the dimensions of the bearing: Width/Outer diameter/Inner diameter.
3. Give the dimensions to a local bearing supplier, they will probably have to order it as it is an uncommon size.
4. Hard part is getting the bearing out of the pulley, if you don't have a press its probably best to get the bearing supply place to do this for you, only takes a second

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All up it should only cost about $35, I'm sorry I no longer have the dimensions for the bearing but it's easy enough to remove the pulley

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