I suggest you call the company that made it or where you bought it from and see if it's still under warranty. If it is, then have them send out a repairman to check it out for you. If it's not under warranty, then you'll have to call a local repair company. Sometimes that noise come from the automatic de-froster that keeps ice from building up.
My suggest will be consult with some local service center or might be a socket problem arise sparking cause noise could repair along . Best of luck ..