Well, I finally got out to pin the wire I thought was the problem, and I realized that I had been looking at the wrong wire last time. The wire I tested was actually the blk/red wire, at the ECU harness at A15, which I believe you said is the ground to the compressor clutch relay? Anywho, I stuck my probe in there to make sure that I would get the same results I did last time, and I got nothing. Tried checking voltage, nothing.
Then, I tried grounding my probe to the car, like it was last time, and some interesting things happened...
The compressor kicked in good and strong, but my car idled WAY down, actually almost stalled a couple of times, and the compressor stayed on whether the heater control a/c switch was on or not. Blew nice and cold though.
So what does that tell me? To clarify, in pin A15 at the ECU harness, if I insert a grounded probe my compressor comes on regardless of whether the A/C switch is on or not. If the probe is not grounded, nothing happens. I have to go in to work in a few hours but I have all day Saturday to work on it if I can't get it today.
[EDIT]
M'kay. Not measuring voltage at the blu/red wire at the ECU. It's making connection fine, I made sure it was pinned properly. I think I've figured out what's wrong but I want feedback to make sure I'm not mixing something up or misunderstanding how this all works.
If I jump the wire that provides the ground to the compressor clutch relay directly to ground, the compressor kicks on. So, the ECU is failing to provide a ground for the relay? And since the ECU isn't getting voltage from the control panel, that makes sense. So...it looks like I have a bad control panel or A/C switch?
The only reason I would think otherwise is that the condenser fan comes on if I have the A/C switch on.