i had a samsung fridge that used to act like this-it happened especially when the voltage was unstable.Try getting your refrigerator checked by an authorized technician from their service center(not by some local repairman without proper technical knowhow-he might make things worse by trying to repair the fridge).Sometime after the rattling started in our fridge,the cooling stopped working completely and we had to trash the fridge and get a new one.A samsung technician who checked it said that the condenser had failed and was unrepairable as it was built into the body of the fridge itself (not an external one like it was with older fridges-so it could not be replaced).
Is this refrigerator a brand new one or a few years/months old?If its the latter,then how old is it exactly?
(posts by various users on quora seem to indicate these issues might also be the symptoms of a failing compressor-only an efficient repairman can confirm if its indeed the case,so better get it checked asap)