Electrical grounds

97 PASSPORT / RODEO 3.4 2-WD
My ac clutch is chattering and i'm told it probably isn't getting 12VDC to the clutch coil. They told be to check the ground and the connections. Connections are good but where is the ground for the AC system, or any others for that matter.

if there is only one wire going to the clutch for power then the ground is through the compressor when it is bolted up. you will see a short wire coming from the clutch and is screwed to the compressor, thats how they ground some of um. also you can get a volt meter and hook it to your hot wire and turn on a/c it should be battery voltage 12.2-13.8