Question for guys with factory A/C

[yellow70GMC]

This is a picture of some type of relay, i know it mounts somewhere in the vicinity of the heater box on the passenger side inside the cab, but i forgot where. It also has a ground wire that i'm guessing needs to be screwed to something metal? Any pictures of where it mounts, or advice would be GREATLY appreciated. It's been 3 1/2 years since i took my system apart, and i'm just now putting it back together. Needless to say, i'm having a hard time remembering some stuff haha

Thanks for looking guys!!