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Brand: LG Model Number: LMXS30766 Main Symptom: Fresh Food poor cooling What happens & when:
Hello, fellow technicians.
I have an interesting case with an LG 3-way refrigerator. The unit is cutting off the refrigerant supply at 14°C, well before it reaches its target temperature.
I’ve already ruled out mechanical and refrigeration system failures. My next step was to use a potentiometer to simulate the compartment temperature sensor.
The results are very telling: with the potentiometer set to 5kΩ, the refrigerator cooled down perfectly to 4°C.
This makes me think the fault isn’t the sensor itself, but that the PCB is incorrectly reading the signal.
Have you seen similar behavior? What are your thoughts?"
I’m not seeing the model number come up on my side, which can happen with units sold outside the US. That said, LG fresh food thermistors are generally pretty similar across their refrigerators. The best way to narrow this down is to test the sensor for temperature accuracy.
A 5K ohm resistance would have the control sensing a temp a little over 40°C. For reference, a fresh food thermistor should measure about 26K ohms at 4°C, 24K ohms at 41°C, and about 16K ohms at 14°C.
If your sensor readings line up with those numbers, then the issue is likely the main control not interpreting the signal correctly. But if the readings are off, then the thermistor itself is the culprit.