Came out to call for a system not cooling properly. Customer was having issues with the system and had replaced the capacitor himself. He stated that the unit worked briefly and then the condenser fan started acting up so he shut it off. I checked the system over and found that the customer had wired the capacitor wrong and could have possibly done more damage to the unit. I changed the wiring on the capacitor to match correct terminals. Cycled system on to test amps, temperatures and pressures of AC system and verify there are no other issues. Upon start up the compressor made a weird noise, but went away within a few seconds. Megohmed the compressor to check vitals and it still checked out. I made homeowner aware that the unit could have had some minor damage done to the compressor, but amps, temperatures and pressures were within proper ranges. I suggest monitoring the system for the next few days and see if by chance the noise comes back or gets worse.