Well, I finally solved my "groaning" compressor noise. It turns out that a couple of the compressor to bracket bolts were loose, one even out completely and rattling against the refrigerant lines. That was actually a good thing, preferable to losing it altogether. I tightened them up and no more noise.
I love it when it only costs time to fix a problem instead of money. I only wish I'd have solved it sooner.
Of course, now I need to put the Jeep in the shop. The air gap on it's A/C compressor clutch is a hair too wide at the upper end of the spec. The clutch starts to get intermittent in its operation after a few miles of heating up. Not having a compressor clutch removal tool nor the time to do it, I'll take it to the honest mechanic around the corner. Yes, the Jeep has a soft top, but it does get hot, humid, and rainy all at the same time here in the Mid-Atlantic. A/C is the only way to defog the windshield!