A coworker had a evaporator replaced two years ago on a 15 year old york 3 1/2 ton AC only split sytem. The guys did a nice job matched up a 4 ton evap (fixed orfice)looked good. Coworker just wanted me to stop by and check refrigerant level he said it had been working great just wanted it checked, the old evaporator was a 13 year annual gas and go untill it got so bad he had to replace it so he told me. I stopped in late one afternoon about 1/2 hour daylight left. Unit running with good amount of water draining from condenstae line. Put on guages and temp probes checked inside return wet bulb/outside ambient dry bulb checked chart and superheat and subcooling right on the button. I did not pull the access cover check compressor amps or anything else but did shut it down and restart just to make sure no compressor noise etc. Everything sounded fine. This was Wednesday afternoon he called me about 10:00 pm last night unit not cooling and of course it was MY FAULT. I ran down this morning and found a loose wire on the compressor capacitor??????? I thought at first he was messing with me but I had to put a new connector on the wire as it was almost burned off so obviously something that had been ongoing. WHAT ARE THE CHANCES OF THIS HAPPENING WITHIN TWO DAYS OF A SIMPLE REFRIGERANT LEVEL CHECK! Anyway I am now be much more careful to check all connections etc even if I have to use a flashlight.