I have a Motorcraft A/C compressor YCC-193 for a '94 351W. It's new and I just received the pigtail connector for it and both wires are black on the pigtail. There are no polarity markings on the compressor. If I connect either wire to positive and the other to ground I can hear the clutch clicking in and out. Does polarity matter here? I've searched and cannot find anything on how this is supposed to be wired.