I called by radiator guy today and he looked at the 1998 Explorer schematic. He said it looked as if it doesn't even need a diode. When he asked me what the motorcraft pigtail looked like, that I just bought, and I said 2 wires with no diode. He said that was probably the "update" pigtail.
-Can I put 12 volts to the hot lead and see if it engages the AC clutch ?