A/C Clutch Wires

Just had a used compressor installed today worked greatfor acouple of minute drive. When i left work today turned it on to see and no air when i got home checked the fuses and under the hood The big 20A fuse #27 was blown.
I then looked at the wires coming from the clutch and the were taped pulled the tape off and it looked a little shady there was a wire with a little diode and another wire that went to the plug. The wire with the diode was spliced into the wire with the plug dont know if it looks like it is factory or hack work.

Has anyone ever looked at the wires and does this sound rite.

To the best of my knowledge the two wires should be voltage and ground. No connection between the two.

On my 97, there is only a single black wire for the clutch trigger, and 2 blue wires at the pressure switch. Sanden U 4691 comp. What did the compressor come out of?

edit- 2 wire ends at the front of the comp- one is the black wire, one disappears under there- presumably grounded?

My 88 has the diode. It also appears in the 88 FSM. Can't seem to find it in the 97 FSM, but those diagrams are hard to interpret.