Re: a GE side by side:I have replaced the heater element in the freezer and the thermistor in the refrigerator side...my freezer has continued to freeze over...is there a thermistor in the freezer side that ought to try to replace? I notice there is something that looks like a thermistor in the bottom of the freezer.

The back wall of your freezer covered with snow? If it is I would suggest you replace the heater and a thermistor - Heater: WR51X10101 Thermistor: WR55X10025. If no snow then it is probably the main pcb: WR55X10656

Replace the thermistors #4 and #5 . 4 is the white bullet looking piece on top of the coils inside the freezer , with 2 white wires . 5 is at the bottom of the freezer , on the left side . These thermistors tell the main board , the temp and the board goes into defrost according to temp the thermistors "tell it " .

OK check the Thermistor, the actual temperature sensor element, and or thermostat if it uses a separate feed.

remove the rear panel in the freezer,and if evaporator coils a solid block of ice,take a hand held hair dryer and melt the ice,then remove the heater located under the coil and test it for continuity,if open replace it with g.e.# wr51x10055 heater element

Open the freezer and look for frost buildup on the back panel. If you see frost, you have a defrost problem. Possible causes are the defrost heater or evaporator thermistor. You will need a multimeter to test the components. The heater should show continuity. The thermistor should be between 10k and 80k? at fridge to freezer temperatures. Anything less than that, the thermistor is bad. Remove the back panel of the freezer to access. The heater is mounted to the bottom of the evaporator coils. The evaporator thermistor is mounted to the top of the evaporator.

If no frost, I would suspect the freezer thermistor. It's at the left lower rear of the freezer or behind a grill on the right wall of the freezer. Same thing, if it reads less than 10k? replace it.

If all the components check good, the only thing left is the main control board. You can find this behind a panel on the back of the fridge.

Part numbers: Defrost heater WR51X10055, thermistor WR55X10025, Control board WR55X10942.

Since the freezer is fine, you are in good shape. Pull off the back cover inside the freezer to inspect the evaporator coils. You should see a light frost pattern. If it is heavily frosted, then you have a open heater element - located at bottom of evaporator. If heater is good and you have heavy frost buildup, replace motherboard and thermistor which is clipped to the top of the evaporator.

If you have frost buildup in the freezer then the most likely cause would be an issue with your defrost system. Theres is a few possible causes the most common would be a bad defrost heater.

1)You can unplug the unit and remove the back panel of the freezer.
2)remove 2 screws holding in the defrost heater (located at the bottom of evap coils)
3) remove 2 wires on heater and ohm heater with meter if shows no continuity then heater is bad
4)according to GE you need to replace defrost heater and thermistor located on top of evap coils.
5)def heater number is wr51x10055 and thermistor is wr55x10025.
6) if heater is good check to see if termination (also on top of evaporator seems to be popped out or bowed)
7) if none of these are the case it would be an issue with your main control board and you may want to call a qualified tech

Pull the refrig out and remove the 8 " x 10 " panel . Behind this panel , is the main control board ( you already know , since you changed it ) . 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 ( pt. number 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 .

Gain access to the main control board , behind the refrig . Unplug the refrig . On the board , remove the blue plug , with 3 larger wires . The terminals on the plug , should be : wire1 , wire2 , space , wire3 . Using a short piece of insulated wire , with both ends stripped about 1 /4 " , insert 1 end into wire2 , and the other into wire3 . Plug refrig back in , and look in the freezer section at the bottom , behind the crisper , to see if a red heater glow occures . May take a minute or so . If no red glow , then the bimetal ( the round 1 " piece , with a blue and a pink wire going to it ) clipped on the top right of the coils , is bad ( since you already replaced the heater ) .
If you get a red glow , then the # 4 thermistor is bad . This is the 1 " white piece , with 2 white wires going to it , on the top left of the coils , which is just clipped on also . I would also recommend replaceing the # 5 thermistor , which is located at the bottom of the freezer , on the left , also with 2 white wires going to it . The number 4 thermistor , is the evaporator coil thermistor , and the number 5 thermistor , is the freezer temp thermistor .

AUTO DEFROST IS BAD REMOVE FREEZER BACK PANEL CHECK HEATER CONTINUITY WITH REFR. UNPLUGGGED IF HEATER BAD ORDER HEATER KIT FOR YOUR MODEL