My Samsung refrigerator was not cooling anymore. The condenser fan was running but the compressor wouldn't turn on. I checked the compressor using a multi-meter which you can do by watching a youtube video like I did and determined the compressor was good. Therefore it could be the start relay/overload or defrost board went bad. I determined the start relay was bad (no burned out signs) using also a multi-meter. I replaced the start relay and overload with a new one and everything was back to normal!