a/c compressor wiring
 

So my a/c doesn't work and summer is approaching... I've been looking at it and yesterday I noticed that the wiring looked wrong. I have ground wires hooked up, but it seems like there isn't a power wire. There is a spot for a wire or connector on the back in the center of the compressor I think, but I was wondering if anyone knew how it was supposed to look or had a wiring diagram or picture. I just need to know where the wire comes from that goes into it.

If the system hasn't functioned in XX years, unless you are ready to replace everything, just roll down your windows.

I don't know when it worked last because I got it a few months ago. I'll just look it up on shop key when I get back in the shop tomorrow I guess. I was just hoping someone on here had any experience and could tell me where the power wire runs from. And I have the equipment to get it working right once I find that stupid wire.