There is already a question about this model not cooling much. On my refrigerator the freezer works fine but the refrigerator part only cools a tiny bit. Was the defrost heater the problem with the question ask before? How do you tell if the defrost heater is not working? Any other suggestions from anyone?
To check out if your fridge isn't cooling due to a defrost issue you will have to remove the back panel in the freezer section. You may have to remove some of the shelves to get that panel out once you've removed the screws holding it in place. If the evaporator (cooling coils) in the freezer are all plugged with frost you have a defrost problem. To troubleshoot this just do a internet search on "fridge not defrosting".