You will need to have someone take a real good look of any signs of oil stains on the compressor, hose's and condenser also look on the hood pad if you see a oily line on it that lines up with the fan belt and the front of the compressor. If all that fails to come up with something you well need to have the a/c system evacuated and see if it holds a vacuum if so have the system refilled with the proper amount of R134 and dye. This is the only way to try and find the leak in the system. Now for the