for a big leak which you have, look for a residue of oil, or put a can of 134 in with the dye in it, in Autozone you can pick up a black light and the glasses to search out the leak. It works. If I had to guess (assuming the condensors not been hit) you probebly have a front compressor seal leaking, look for oil there, the rings that also seal the compressor halfs over time start to leak also.