Frig Problem

[jayarmstrong1]

I made a service call yesterday on this GE SXS refrigerator.
According to the customer, my visit makes the tenth
time that someone has worked on this frig in the last 12 months.

According to the customer, the frig will go into a deep freeze mode
followed by a strong defrost mode that will thaw the freezer and warm up the frig section. The other techs have replaced the main control board, the temp control board, the heating element, the defrost terminator,the freezer thermiostor.

When I examined the unit, I found a wire on J2 of the main board that had been cut. This wire is supposed to be for the fresh food (FF) section. I believe that the main PCB is not receiving the signal from the FF thermistor so it try to cool more, resulting in the system over-freezing and then going into an extended defrost cycle.

Any thoughts would be appreciated.

Model GSS25SGMFBS

[Nugget]

Have you checked to be sure the fresh food door is aligned with the freezer door? Sounds simple, but if the switch is open all the time, the board will "over defrost" because it calculates the defrost time needed based on this input. Is the fresh food and freezer working regularly otherwise?

[Nugget]

Also your open thermistor theory sounds like it could have some merit as well. If the circuit is open, the board could calculate the fresh food temperature is too high.

From the manual:
NOTE: The thermistor’s resistance has a negative coefficient. As the temperature increases, the Thermistor’s resistance decreases.

It seems like the compressor would be running all the time if this input is seen as "Open" though. Is it always running? Also are the temperatures in the freezer and fresh food side normally within range?

[Repair-man]

If the other thermisters have not been changed (2 in freezer, 1 in FF) they need to be, as the thermister design has beed updated. Also, it may be normal to find a cut wire on the J2 plug, since the instructions that come with the new motherboard says to cut this wire on certain units (it goes by serial number). I believe it eliminates one of the lesser used thermisters, such as the ambient temp one on some models. If the thermisters do not have a blunt end on them, they need to be replaced.

The one in the FF section is part of a damper kit, and can also cause the board to go into pre-chill as you described, however, the usuall complaint is frozen veggies and eggs in this case.

What are the temps running in this unit?

[jayarmstrong1]

In attempting to run the self-diagnostics, the service manual says to press the HOLD button for 3 seconds to begin the selected test. There is no HOLD button the this display. Where is the HOLD button.

On J1 of the main control board there is no wire at J1-1 and J1-2 has been cut. According to the service manual J1-1 is the FF thermistor #1 and J1-2 is the FF thermistor #2. It would appear then that neither FF thermistor in the refrigerator section is connected and communicating with the main control board.

[Repair-man]

Only on certain serial numbers runs was the arrangement changed. The thermister #2 was an ambient temp sensor hidden under the top door hinge cover. It was labeled as a #2 FF thermister on the diagram. The #1 was indeed connected to the thermister at the damper in the FF section. On your model, the J1-2 wire was likely designated as the main FF thermister in the damper area, which you could confirm by running a continuity test to the connections in the damper thermister from the cut wire.

I usually replace all 3 thermisters when I find this issue. You may need to reconnect that cut wire if it leads to the damper thermister.

[Nugget]

There is no hold button on some models. It will enter diagnostics, but there is no way to initiate the actual sequence. If you look on the temperature control board itself, there will be a place where they used to solder on the hold button (or maybe do on some models still).
 
If you take a look at my post GE profile Adaptive Defrost, you may get some clues. I was having the exact same issue and it turned out to be the door switch was not adjusted properly (very expensive adjustement in the end)