My refrigerator cools perfectly .the only problem is a very loud huming vibrating sound comes from it when the compresor is running. could it be from the Ptc starter?
The PTC starter would not cause a loud humming vibrating sound. It sounds more like it may be a copper line vibrating against the cabinet or against another line. Check the lines and the condenser coil to make sure that the vibration is not coming from them. This is the most likely scenario.