2000 Durango - AC Clutch wiring issue

I have a 2000 Durango with 5.2L V8. The return side of the AC Clutch (black wire) shows very high resistance to ground (and the clutch won't pull in). If I jump the black wire to the chassis, the clutch does pull in.

Can you tell me where this wire is physically connected to the chassis or ground, and perhaps how it gets there?

I suspect this wire also is the return for the left front O2 sensor because the computer says that sensor is bad.

All this happened when a mechanic replaced the belt and belt tensioner. I suppose it could be just a coincidence.

Thanks,
John