pins 16 and 23 should be power and ground to the compressor
16 (ground)is a red wire and 23(clutch power) is blue and white
21 is pcm power for the a/c and 22 is pcm control for the wide open ac cutout
if you just 21 to 23 it should turn on the ac as long as the ground is good in the ccrm. its usually just the relay that goes bad so that should do it
lol its been a while since i worked on one of those. if you need it I can print screen the wiring diagram and connector pinout from the ford manual