It should start and stop smoothly with a steady hum. Loud rattling, clunking, or grinding noises are red flags for a failing motor.
Look at the condenser coils behind or under the unit. Heavy dust buildup suggests poor maintenance, which puts extra strain on the compressor. 10 Tips to Buy Used Appliances | A Detailed Guide buy second hand fridge
Close a piece of paper in the door; if it pulls out easily, the seals are worn and will lead to higher energy bills. It should start and stop smoothly with a steady hum