A/C keeps blowing fuse

My a/c has been working fine since I bought it at 104000 miles but a month ago it stoped so I start the check list and the 10amp fuse is blown so I replace it check it and as soon as turn the a/c on it blows but when I bought it I notice the wires running to the compressor were put together with two wire nuts I guess where the harness was so someone had issues before or maybe the truck didnt come equiped with an a/c its a base model that came from an power company but digging around I notice that there was a little capasitor linked to the two wires running to the a/c clutch but I was wondering how to test the clutch without going through so many fuses or test the complete sys. To find out why its blowing the fuse there was no symtoms leading to the problem no noise, no difference in how cold it got so I assume its grounding out before its suppose to but how would u test to see if the clutch will engage how many volts dose it take to engage it or is a proceedure to do this