[jimek6]

My GE refrigerator Model GTS 22KMARBB purchased in 2002 has a defrost problem.

It has a main control board which controls both the compressor and the defrost heater.I have had the main control board and the defrost thermostat replaced but the problem persists, the evaporator coils freeze up every ten days or so.

The defrost heater gets very hot when a jumper is placed between the “line” and the “defrost” terminals on the control board.

The service technician says he has no other ideas on how to fix the problem.

What do you think? Could a thermistor be the source of the problem?

[Drags1998]

OK, lets look at the big picture,If the coils are FULLY FROSTED, and you "JUMP" the terminals on the board and the HEAT comes on, We know that the HEATER and the DEFROST THERMOSTAT are OK!!! That ONLY leaves the CONTROL BOARD!!! Replace the board and you should have it!!!!

[jimek6]

But the very first thing that was done was to replace the control board, then later the defrost timer. My main concern now is whether or not a thermister might somehow be the problem.

[Drags1998]

I dont think so. You said that they replaced the control board, then later they replaced the defrost timer, I'm confused???? The defrost timer is built into the control board,and cant be changed unless you change the MAIN BOARD!!! I stick to my opinion in the first post.

[jimek6]

My mistake. After the new control board did not fix the problem, the defrost thermostat was replaced. The wiring at the thermostat was in bad shape, so it looked like a good bet that this would fix the problem, but it did not. The defrost heater gets hot when a jumper is placed between the line and the defrost connector on the control board. The control board, the defrost thermostat and the heater are the three main components involved in defrosting. What does the thermistor do?

[Drags1998]

The THERMISTER is what senses the temp. in the freezer and the refer sections of the unit, and the board decodes the signal it sends by varying resistance to the board. It has NOTHING to do with the DEFROST CYCLE!!! If you "JUMP" the board and the defrost works, YOU NEED A BOARD!!!!!!! PERIOD!!!!!

[jimek6]

If that is the case, why would I have multiple control board failues all affecting the defrost cycle? The original board lasted six years. The second one about 90 days, and the third one about 30 days. Is GE having control board quality problems? Who could I talk to find out? I hate tpo think of replacing a six year ole refrigerator because of a control board problem.

[Drags1998]

They have had a FEW problems with the boards, I have changed maybe a dozen of them and NEVER had to go back on one, Also, when I install one, It comes with a 90 day part warantee!!!!

[v2k04]

If I may reply and argue the fact that the thermistors have nothing to do with the defrost........ the thermistor clipped to the evaporator has a lot to do with the defrost if the thermistor is bad it will never tell the board to go into a defrost I would replace the thermistors The freezer section has two thermistors one on evap and the other down by drain. One senses freezer temp the other communicates with the board for the defrost cycle

[Drags1998]

I can not argue that point, However, if the temps are OK until it frosts up, then its NOT the thermistor, I have NEVER changed a thermistor!!(not to say they don't fail} But so far, boards 12-15, defrost therms.35or so, defrost heaters 60 plus so far!!!!