The defrost is not working,.The evaporator coil in the inner section of freezer is got blocked by ice .
Try manual defrost reset procedure: ----
First unplug the unit from main power outlet. Then empty whole unit completely. Then keep both the doors open. Wait for 24 hours. All the ice collected on the coils and in the freezer section will get melted. Clean the water from the sections. Then Connect the power cord of the unit to main power outlet after 24 hours/.Then set the temperature to normal in both fridge and freezer section. It will take near to 4 hours to get run in its proper cooling cycle. Then check, if the problem returns again. If the same problem occurs then it's defrost problem. The defrost board and the defrost thermostat/heater is not functioning properly and it has to be checked and replaced. -------
If it's again building up ice that means the unit is not defrosting. It's starting the cooling procedure, and then while defrosting, it's not working. The defrost assembly consists of three main parts. The defrost thermostat, the defrost heater and defrost board. Any of the one is not functioning. When thermostat sense the maximum cooling, it triggers the defrost heater to start heating and this defrosts the ice collected on the coils and the system works. Both thermostat and heater are controlled by defrost board. First the thermostat and defrost heater to be checked, if both check ok by meter and visually, then its defrost board causing the problem. You can get required parts from online sites like: --- www.repairclinic.com or from searspartsdirect online site.
