Came out to call for a system not cooling properly. Customer stated that the system was running, but the temperature in the home was rising and they couldn’t feel any cool air. I checked the system over and found the fan motor running, but the compressor wasn't operating. Customer cleaned the unit before I arrived and had replaced the capacitor. It was wired up correctly and had the right rating. I checked to see if the compressor was hot and it wasnt, but noticed that there was oil residue on part of the coil. Told customer there’s a good chance he has a leak, but I needed to try and get the compressor operating before I could check pressures. Discussed with customer about trying a hard start kit to get it going and he wanted to try it. The hard start kit got the compressor going and I checked pressures and found the unit low on refrigerant. When discussing options the compressor made a noise and cut out, then wouldn’t come back on. Let customer know that the compressor is failing and