I have had this car about a year and was told by the PO that the AC had not worked in a long time. I turned on the AC switch and bypassed the low pressure switch on the drier but the compressor didn't engage. There is a junction in the wire going to the compressor. I pulled that apart and have power going to the compressor. I fear this means the clutch is bad, at least. So, three questions:

1) On top of the compressor is a small white box that the power lead goes into, with wire coming out the other side to the clutch itself. Is that just a junction, too, or is it by any chance a fuse that might have blown?

2) If it is the clutch does it make sense to only replace the clutch or should I do the whole thing?

3) Any wisdom in grabbing a compressor from a junk yard or is it smarter to buy and new unit or even upgrade to a better unit?