LG Refrigerator: Not Defrosting
Quick answer: When the automatic defrost system stops working, frost accumulates on the evaporator coil and the back wall of the freezer, airflow drops, and the refrigerator section slowly warms.
- Unplug the refrigerator before removing the evaporator cover or testing the heater.
- The defrost heater can be hot; let it cool before touching it.
- Never chip ice off the evaporator with a knife or screwdriver; use warm air or let it thaw.
Why is my refrigerator not defrosting?
When the automatic defrost system stops working, frost accumulates on the evaporator coil and the back wall of the freezer, airflow drops, and the refrigerator section slowly warms. The usual causes are a burned-out defrost heater, a failed defrost thermostat, a stuck defrost timer or control board, or a faulty defrost sensor. A door gasket leak can also cause frost, but usually near the door rather than on the back wall.
Our fitment data covers 1,515 LG refrigerator models and 3,032 LG refrigerator parts, so the part links below are filtered to this brand; always confirm your model number before ordering.
Most Likely Causes, in Order
1. Defrost heater
The heater melts frost off the evaporator several times a day; when it burns out, frost accumulates until the coil is a block of ice and air cannot pass.
How to check: Unplug the unit, remove the rear freezer panel, and look at the heater below or through the coil. Test for continuity across its terminals with a multimeter; an open reading means it has failed. Frost covering the entire coil evenly is the classic sign.
Fix: Replace the defrost heater. (Difficulty: Moderate)
Matching LG parts:
- Defrost Heater Assembly 5300JB1102H — $95.48 · 152 models
- Fresh Food Defrost Heater MEE62805106 — $95.46 · 39 models
- Defrost Heater Assembly MEE62225167 — $95.48 · 24 models
2. Defrost thermostat
The defrost thermostat closes when the coil is cold to allow the heater to run; if it fails open, the heater never gets power.
How to check: With the unit unplugged and the thermostat cold, below about 20°F (-7°C), test it for continuity; it must be closed when cold. If it reads open while frozen, it has failed.
Fix: Replace the defrost thermostat. (Difficulty: Moderate)
No LG part for this cause is in our catalog yet; search by your model number.
3. Defrost timer or control board
The timer or board decides when to stop cooling and start the heater; if it is stuck in cool mode, defrost never happens.
How to check: On mechanical timers, turn the dial slowly with a screwdriver until it clicks; the compressor should stop and the heater should sizzle within a few minutes. If it never advances on its own, replace it. On electronic models, test the heater and thermostat first; if both are good, the board is suspect.
Fix: Replace the defrost timer or the control board. (Difficulty: Moderate)
No LG part for this cause is in our catalog yet; search by your model number.
4. Defrost sensor
Electronic units use a sensor on the evaporator to decide when to defrost; a bad reading can keep the heater off.
How to check: Unplug the unit, disconnect the sensor, and measure its resistance; compare with the value on the tech sheet. Also inspect the sensor clip for corrosion.
Fix: Replace the defrost sensor. (Difficulty: Moderate)
Matching LG parts:
- Refrigerator Defrost Temperature Sensor 6615JB2005M — $10.30 – $33.61 · 2 models
5. Door gasket
Humid air leaking past a bad seal freezes on the nearest cold surface and forms frost that the defrost system cannot keep up with.
How to check: Frost near the door edge or on packages, rather than on the back wall, points to a seal leak. Do the paper test around the gasket and check that the door closes fully.
Fix: Clean, reshape, or replace the door gasket. (Difficulty: Easy)
Matching LG parts:
- Refrigerator Freezer Door Gasket MDS38201424 — $71.06 – $85.17 · 219 models
- LG Refrigerator Freezer Door Gasket MDS38201426 — $70.63 – $86.85 · 173 models
- LG Kenmore Refrigerator Freezer Door Gasket ADX73350925 — $82.40 – $92.35 · 145 models
Other LG parts the catalog tags for this symptom
- Freezer Door Handle (Stainless) AED37133117 — $91.32 – $108.10 (door stuck; door won't close; handle broken)
- Fresh Food Door Handle AED37082977 — $80.64 – $106.65 (door stuck; door won't close; handle broken)
- Refrigerator Door Handle AED73593202 — $62.91 – $79.15 (door stuck; door won't close; handle broken)
- Refrigerator Defrost Heater 5300JK1005K — $81.41 – $121.92 (frost in freezer; ice buildup; not defrosting)
- Refrigerator Door Handle Assembly AED37133123 — $262.44 – $289.87 (door stuck; door won't close; handle broken)
- Refrigerator Heater Sheath 5300JB1092D — $101.04 – $189.60 (frost in freezer; ice buildup; not defrosting)
Popular LG refrigerator models
Confirm the model number on the rating plate before ordering. Each model page lists every compatible part.
Frequently Asked Questions
How do I manually defrost to get by until the repair?
Unplug the unit, empty the freezer, leave the doors open with towels on the floor, and let it thaw for 8 to 24 hours. Cooling will return for a few days until the frost comes back.
Why is the freezer frosted but the refrigerator warm?
The frozen evaporator blocks the airflow the refrigerator section depends on; the freezer stays cold because it sits next to the coil.
How often does a refrigerator defrost?
Typically every 8 to 12 hours of compressor run time, for 20 to 30 minutes each cycle.
When to Call a Professional
Call a technician if the heater, defrost thermostat, and sensor all test good, or if the control board must be replaced; misdiagnosing a board is an expensive mistake.