Not much to go on here, but my guess is it's a hermetic system. They usually don't have leaks unless somebody serviced it and used piecing valves and didn't braze in real service ports.
If it runs at all, I'd check the condenser coil for dirt and prove the condenser fan is running and running at speed. The chance of the evaporator being dirty is slim, but you would probably see ice buildup on it if it was dirty or there was a problem with the evaporator fan.
If it has auto defrost, the defrost timer may be stuck in the defrost cycle or has gone bad.
Tommy
