There is also one more procedure for same system,that is manual defrost reset procedure. The procedure is as follows: ----
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. Then its defrost board problem. -------------
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 from online sites like: --- www.repairclinic.com or from searspartsdirect online site.
-------------
Refrigerator is not cooling properly?
http://technoanswers.blogspot.com/2011/06/refrigerator-is-not-cooling-properly.html
Both refrigerator and freezer not cooling properly in refrigerator?
http://technoanswers.blogspot.com/2011/06/both-refrigerator-and-freezer-not.html
----------------