I believe that chassis also has an electric clutch on the main fan behind the radiator and that would be the sensor for the clutch engagement................

I will even give you a little tutorial on that 3 wire sensor/ sw.

It is the 105/115 sw
It closes one set of contacts at 105 C for the high fans to prevent overheat condition of coolant and it closes the other set at 115C to kill the a/c compressor in the event the coolant gets into that danger zone.
So, the diagnosis on yours is an internal short to ON for both contacts , giving you both complaints of Constant High Fan and NO A/C...simple as that.

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A Dalton