The A/C clutch on my 1999 Suburban engages with the key. If I remove the A/C relay in the underhood fuse block, it goes out, but when the relay is in, the clutch stays engaged regardless of any of the settings on the dash controller. I also disconnected the pressure switch connector (at the accumulator) but it still stays on(so it doesn't seem to be the pressure switch that's bad). I followed the wire from the relay to the ECU and found that it becomes live with the key on position. Should I get power through it with the key on, or is it supposed to be controlled through the dash switch? If not, will replacing the ECU fix the problem, or could it be just a wire? I went to a dealer and was told that I could replace the in-dash controller, but if it didn't fix the problem then I'm out ~$250. I could also replace the ECU to see if that's the problem, but if not then I'm out ~$300(plus the cost of programming). Since the parts are electrical there's no chance of returning either of them once they are used. I'm pulling my hair out trying to figure this mess out!!! Any ideas on how I can troubleshoot further to be certain of what needs to be replaced? Thanks for any replies!!