Ok so for the past two months or so every now and then when the AC is running I get this high pitched horrendous sound. At first I thought it was coming from the engine so I checked the belts and all that, no problems. A few days ago I realized (which I should have from the start) that it's from the rear speakers. For some reason turning off the AC for a second then turning it back on seems to make the problem go away for a minute. This does not happen while the AC/Vent is off.

My friend and I took off the face plate for my after market stereo (was on the car when I bought it) and AC controls to take a look. We found a wire that seemed to be spliced into another wire that went into the connector for the AC/Air Flow/Vent control (the middle one). We took off the electrical tape and found that a wire from that connector and another wire that was coming from... somewhere... were connected together with some kinda connector and then shoved into a piece of insulation. These are both (apparently) grounding wires. One is definitely a ground as it's all black, the one coming from the connector is black/brown.

I have taken a few pictures of it, plus where I think is the only spot I can possibly ground it as far as I can tell. Unfortunately, the wires are too short to reach that spot. If I get another wire that is the proper gauge can I splice them together and then try and connect them? Is this kinda thing stock? I can't tell if this other wire is going to my stereo or not and didn't have time to try and trace it further because unfortunately, it got dark and I have no garage (Air Force dorm life).

I'm going to go ahead and provide the few pictures I took.

 

That wire looks black with a white stripe.....

You're sure it's black?

 

There's two. One that's black/light brown and one that is solid black both going into one "connector" thing at the tip. The black/light brown one comes from the connector that plugs into that AC control button, the other goes into that grey shielded cable and goes off somewhere.

 

yea doesn't look normal at all, try grounding the a/c controls somewhere else. I don't remember seeing something like that when I installed my radio, the connector didn't have a ground like that. but it could be why your getting the noise, its grounded at the same place as your radio.

 

That's kinda what I figured but that's going to be one hell of a chore. There's nothing under there to ground it to except for that spot where there's already another ground. Oh well, gotta do what you gotta do. Thanks for the help.