Past winter i did a s13sr red top into a s14 with A/C. The harness was from wiring specialist. So i tried to turn the A/C on and i heard the fuse blow in the bay.so I checked the compressor for seized clutch but nothing, looked at the harness for shorts but nothing came up. So i put in a another fused and tried again. But this time i notice when i clicked the A/C button the defrost also turned on for a sec. So i pressed the Defrost button and somehow my A/C is blowing cold air and it still had a blown fuse in the holder. 
Any idea why my a/c system is acting like that.