Refrig. is about 4-5 years old and regrig side

Pull the refrig out , and remove the rear panel . Do you feel the compressor running or hot ? If not , then the main control board is bad . Your board is on a recall list , pt # WR55X10552 . The new board number , is WR55X10656 . If the compressor is not running , call GE , since this board is still covered under warranty . http://www.scribd.com/doc/13371507/Ge-Motherboard-Concession-Letter .
If you have frost built up on the rear inside freezer wall , to check for the problem , pull the refrig out and remove the 8 " x 10 " panel . Behind this panel , is the main control board . Unplug the refrig . Remove the BLUE plug from the board , with 3 larger wires going to it . Looking at the blue plug , the sequence will be wire1,wire2,space,wire3 . Get a short piece of insulated wire , and strip about 1/4 inch from each end . Insert 1 end into wire2 , and the other into wire3 . Plug the refrig back in . After about 3 min , look in the freezer , at the bottom , behind the crisper , look for a red glow . If no red glow , unplug the refrig , and reassemble the plug and cover . This no glow , indicates a shorted defrost heater WR51X10055 . It is also advisable to replace the defrost thermostat ( pt. number WR50X10068 ) when replacing the heater . To access these parts , you will have to remove the inside rear wall of the freezer . The heater , is at the bottom of the coils , held on with 2 screws , and the thermostat , is the 1 " cylinder , with a blue and pink wire going to it , clipped on the top left of the coils .
If you do get a red glow , then the # 4 thermistor is bad . This tells the main control board , the temp of the coils , if they need defrosted , when they are thru defrosting . This thermistor is the 1 " long , torpedo looking piece , clipped on the top left of the coils , with 2 white wires going to it . Part number WR55X10025 . It would be advisable to also replace the # 5 thermistor , located at the bottom of the freezer , slightly in front of the drain , also with 2 white wires going to it , slid into a housing . This thermistor , is the freezer thermistor , which tells the control board , the freezer temp , when to cycle off , associated with the fan speed also .

Look inside the freezer on the back wall. If there is ice on the back wall the defrost heater and defrost thermostat are the usual suspects. They are both in the freezer behind the back panel.
Look for a deformed defrost thermostat. The glass heater will look burned. Both can be checked with a meter set for continuity. No continuity equals a bad part. Remove the wires from the parts before checking or a false reading will occur.