[bf24tbh]

Same question about same symptoms of refrigerator side freezing up for GE tfx20JR type about 20 yr old. Would like to know where to start checking?
Bf24

[drtom4444]

More than likely your defrost system is not working. There are three parts: the defrost timer, the heater and defrost thermostat (called the defrost terminator). The last two parts are in the freezer and should be replaced together. You need a multi-meter to check everything out. First, remove cover to freezer coils (unplug unit first) and you will see wires coming into freezer going to the fan and to the defrost heater. The wires going to the heater will have a t-stat wired in series and it is clipped to the side of the coils. Unplug the wires where they supply the t-stat and on the other side where it supplies the other side of the heater. Keep these wires away from the coils where you can test them with a volt/ohm meter. Find defrost timer and turn it until it clicks and put meter on ohms and see if you have a reading of about zero from one side of the plug to one wire then check other wire for same. If you read no voltage the timer is bad. Then ohm out the heater and see if you have continuity below 100 ohms. The terminator (a round button t-stat attached with a clip to side of coil) will have to be below 32 degrees to test it, but will read zero when it is that cold. Plug the parts back together and see if refrigerator comes back on in about 15 minutes. If it does not then the timer is not advancing and the timer motor is bad. Replace timer if this is so. You also want to check the evaporator fan in freezer and see if it is blowing. If so, then you know the problem is in the defrost system, but maintenance is still needed on that motor. If possible, oil the motor by putting a little oil on rear shaft into felt pad at rear of motor. Also, check under unit and clean out dust and dirt twice a year. Be very careful when working around coils as you can easily break a cap tube or puncture the thin aluminum coil and ruin the unit. Don't make any sharp bends moving things out of the way. DrTom4444