A/C clutch not engaging on my 90 4x4

[ratedZX]

i checked all the fuses in the cab and under the hood(none of wich are labled heat or A/C).the thing was working when i test drove the truck but when i bought it a few days later the sw wont light up and the clutch wont engage.i thought it might have leaked out but i hooked my guages up and its full.any ideas where to look would help,perhaps theres a fuse i cant locate?

[Can1]

quick test to check the a/c pump....unplug the pressure switch on the accumilator,take a paper clip or piece of wire and cross the two connectors in the plug(not on the accum.)if the pump is in good working order it should engage

[ratedZX]

i went to my local goodyear and refered to mitchells wiring diagrams.turns out theres a 3rd fuse box behind the glove box.the ac fuse was there and blown.i replaced it and its been working all day(yes i put the recomended fuse)