AC problems are a fickle bitch. Not sure if this helps: car is a 05 with BOE supercharger and older X2 EFI. Had the same problems and troubleshooting outcomes as you. I could run a long wire from the front relay to the compressor and it would kick on. So the relay was fine. Behind the engine and under the ECU was the connector for the relay/compressor. It was only two wires and when I disconnected it I found that power from the relay was getting to the connector. I could put power to the compressor side of the connector and the ac clutch would kick on. Turned out that when the the connector was put together one of the pin would be pushed back in the housing and not make connection. I could carefully connect and make the proper connection, but sometimes it will work back to not making proper connection. I have ordered a new connector and will be replacing it.
"It always seems to be something!"