LG Refrigerator Thermostat Replacement

LG refrigerators run temperature through thermistors and the main board, but the defrost circuit still leans on a simple mechanical thermostat. Knowing which thermostat your model uses decides the whole repair.

Defrost Thermostat vs Cold Control#

The defrost thermostat is a bimetal disc clipped to the evaporator coil. It closes once the coil chills below about 30–35°F and opens again when the coil warms past roughly 50°F during a defrost cycle. Because it sits in series with the defrost heater, it only lets the heater run when the coil is genuinely cold — and when it fails open, the heater never fires. Frost then builds on the evaporator until it chokes airflow and the fresh-food side goes warm.

Older LG models with a manual temperature dial instead use a cold control thermostat, a capillary-tube device that switches the compressor on and off directly. Newer electronic LGs have no cold control at all; a stuck compressor on those points to a thermistor or the board, not a dial thermostat.

Match the Symptom to the Part#

Testing the Bimetal#

Unplug the fridge and pull the rear freezer panel to reach the evaporator. The thermostat is the small two-wire disc clipped to the coil tubing. Cold, it should read continuity (closed); at room temperature it should read open. A thermostat that reads open while still freezer-cold has failed and needs replacing.

Replacing It#

The disc simply unclips. Release the two wires, clip the new thermostat onto the same tube run, and reconnect. If ice buildup drove the failure, defrost the whole compartment first — unplug the unit with the doors open for about 24 hours and lay down towels for the melt. While the panel is off, test the defrost heater and the timer or board too, because the thermostat is only one leg of the circuit.

Part Numbers#

The LG defrost bimetal thermostat is 6931JB2002Q. Many technicians replace the defrost heater, 5300JB1092A, at the same time, since a failed thermostat often lets an ice load stress the heater and both live behind the same panel.

The Whole Defrost Circuit#

Three parts share the job: the timer or control board starts a defrost, the heater melts the ice, and the thermostat cuts the heater once the coil is warm. Any one failing looks the same from the front — a frosted coil and warm food. Test all three before ordering, so you fix the actual fault instead of the easy guess.

Holding You Over#

You can limp along by defrosting manually: unplug, open both doors, and let it thaw for about 24 hours with towels down. It is only a stopgap — the frost returns within a week or two until the defrost part is actually replaced.

Thermostat or Something Else#

Because a frosted evaporator looks identical whether the thermostat, the heater, or the timer failed, resist swapping parts blindly. The bimetal thermostat is the quickest of the three to rule in or out with a meter, so start there, confirm it reads open while still freezer-cold, then move on to the heater and the control board. Buying all three at once is tempting, but a single meter check usually narrows it to one. Once cooling is restored, a light quarterly wipe of the door gaskets keeps humid room air from adding to the frost load the defrost system has to clear. Less ice reaching the coil means fewer and shorter defrost cycles, which in turn extends the life of the thermostat, the heater, and the board that drives them.