My GE side x side is not cooling enough and the coils behind the panel in the freezer are icing up. I replaced the heater about 6 months ago and it solved the problem. I took the heater out today and had it tested at a parts place and they said it was O.K. What should I check next?

Check the heater defrost termination thermostat and the defrost timer. Those are the other tow items in the defrost circuit. Usually when I service a unit with a defrost proble I always replace all 3 parts to pervent further problems for awhile. You replaced the heater so now replace the other two parts.

BTW I guess the little blower fan is working in the unit?

I also replaced the timer and the round object that plugs into it that I assume is the thermstat before I replaced the heater. The fan is working.

Then it is one of the other items you already replaced. There are only 3 items that can cause that problem. Check your wiring to make sure it did not come loose also. Just because you replaced the part does not mean it has not gone bad again.

One thing I noticed different this time is that last time it was heavy frost. This time it is frost at the top area of the coil and thicker ice toward the bottom.

There are other things like the fan that I asked you about and the fan switch but the first things I test are the defrost parts already mentioned because of there known problems. It is possible the refrigeration system could be having problems also but I hope not for your sake since that can be major $$$$. In fact I do not replace compressors in refrigerators anymore I just tell the people to buy a new Ice Box since by the time you spend all the $$$ something else will go wrong. Since I am a old guy I usually call refrigerators Ice Boxes. LOL

Thanks for your answers. The refrigarator belongs to my daughter and I just talked to her and she said that since I had the heater checked and melted the ice yesterday morning that the coil is still relativitaly frost free but it does look like ice is starting to form at the bottom of the coil