Mazda Repair: AC electrical harness/system, magnetic clutch, thermo sensor

Question
I have recently purchased 1990 Miata 5 speed.  It has all the hoses for AC and it's been charged without any leaks.  However, It won't kick the compressor in.  It looks as someone did macgiver with AC wires (actually most of other wires too).  How can I trace to see if all the wires are connected and if now where can I get parts as I called dealer they said it's been discountinued.  Thanks for your help.

Answer
Check the single wire lead from the compressor for voltage, AC switch on engine running.  (located at the front PS fluid reservoir mounting bolt)

Disconnected, if you apply 12 volts to wire compressor side the compressor should engage for test purposes. (do not leave it like that however, just a test of the magnetic clutch windings)

Three common possible faults if the clutch is operable;
the thermo-sensor at the evaporator (can be jumped for testing)
the high pressure sensor (inline passenger side near headlamp motor) (can be jumped for testing)
the system relay (attached to the headlamp retractor passenger side)

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