I have a 92 240 with ac converted to 134. The ac compressor clutch recently stopped engaging. I'm getting power from the switch. But I found I'm getting negative current from the little black wire on top of the compressor that goes to the magnetic clutch. The wire goes about ten inches up and connects to a wire that gets positive current from the switch. Has anyone else experienced this? It seems like the little black clutch wire is grounding. Any ideas? Thanks.