What would make my whirlpool freezer part of refrigerator keep running almost non-stop just to keep it cold?

Two days ago I noticed that the ice-cream in my freezer had began to melt at 30 degrees F. It has stayed around ten degrees since but is constantly running. We turned off the unit and took off back of freezer. There was no frost build up. My whirlpool ET1CHMXKQ04 is less than five years old and has already had a new ice-maker, defrost timer, thermostat, and defrost thermostat. All my other experiences with whirlpool have lasted 20+ years. Any ideas or is this a lemon?