I have had this problem twice with my GE GSS2010EMBWW. The first time I called a GE tech and watched him defrost my coils and replace the heater. There are only 4 screws holding the evaporator cover on and 2 for the heater. The second time I ordered a new heater and replaced it myself. That ws a bad guess, the old heater ohm'd good, but what the heck. Still no defrost so I ordered both the thermister and thermostat. Both are cheap and shipping and handling was the same for both parts, about $30. Cut and spliced both parts in and I now defrost.

I did check out both old parts, it appeared to be the thermostat. With two of three parts failing within 8 years I am glad I replaced all three defrost parts.

Pay attention to where the thermistor and thermostat clip onto the top of the coils.

My problems all dealt with the freezer not defrosting. This would cause the refrigerator (cold food) side to get warmer and warmer, but the freezer stayed frozen (I never checked the temps in this side). If this sounds like your problem, start by pulling the back panel inside the freezer. All you have to do is remove the shelves and the 4 screws holding the panel. If the coils are iced over little or no air can be pulled up over the frozen coils, therefore little or no cold air gets blown into the refrigerator side.

If the coil is frozen over, defrost it with a hair dryer or heat gun. Pull out the defroster that is attached near the bottom of the coil and use an ohm meter to check to see if it is bad. Most of the time this is the problem. If it is good it must be the thermostat or thermistor. I only have one thermistor on my freezer side to deal with.

If your coil is frozen and you defrost it and the whole refrigerator works properly. then you probably don't have any problem on the cold food section, just the freezer side. You also will have time to order the parts you need before the coil freezes back over.

Stick a paper towel in the drain hole to keep any screws from dropping in it, remove the towel for defrosting.