LG Refrigerator Error Code Er dH: Defrost Heater Circuit Failure
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What Error Code Er dH Means
The Er dH code means the defrost heater circuit is not working. During automatic defrost cycles, the control board sends power to a glass-tube or calrod heater mounted beneath the evaporator coils. This heater melts accumulated frost. If the heater, its wiring, or the defrost control circuit fails, frost builds up on the evaporator until airflow is completely blocked. The freezer warms up first, then the fresh food section follows.
Common Causes
Burned-out defrost heater
The heater element opens over time from thermal stress. It receives voltage but produces no heat. This is the most frequent cause of Er dH.
Failed defrost thermostat (bi-metal)
The bi-metal thermostat sits on the evaporator tubing. It is supposed to close the circuit when the evaporator drops below a set temperature. A failed thermostat stays open and blocks power to the heater.
Defective main control board
The relay or triac on the main board that initiates the defrost cycle fails. The heater and thermostat test fine, but they never receive power.
Broken wiring in the defrost circuit
Wires in the defrost harness crack from repeated thermal expansion and contraction. A single open wire stops the entire circuit.
How to Fix It
- 1
Confirm frost buildup
Open the freezer door. Remove all food and shelves. Remove the rear evaporator cover panel (4-6 Phillips screws). Heavy frost or a solid sheet of ice on the evaporator coils confirms the defrost system has failed.
Unplug the refrigerator before removing the evaporator cover.
- 2
Test the defrost heater for continuity
Locate the defrost heater beneath the evaporator coils. It is a glass tube or metal rod running the width of the evaporator. Disconnect both wire leads from the heater. Set a multimeter to the 2K-ohm range. Touch the probes to the two heater terminals. A good heater reads between 20 and 50 ohms. OL means the heater element is open and needs replacement.
- 3
Test the defrost thermostat (bi-metal)
The bi-metal thermostat is clipped to the evaporator tubing. Disconnect its wires. At room temperature, the thermostat should read OL (open). Place it in a cup of ice water for 3 minutes. Test again. It should now read 0 ohms (closed). If it stays open at cold temperatures, replace it.
- 4
Manually defrost the evaporator
Use a hair dryer on medium heat to melt all frost from the evaporator coils. Keep the dryer nozzle 6-8 inches from the coils. Catch melt water with towels placed at the bottom of the freezer. This step restores cooling while you wait for parts.
Never use a heat gun or open flame. The evaporator coils and surrounding insulation can be damaged by excessive heat.
- 5
Check the wiring harness
Trace the defrost circuit wires from the heater to the main control board. Look for cracked insulation, broken conductors, or melted connectors. Repair any damage with high-temperature wire connectors and heat-shrink tubing.
When to Call a Professional
If the heater or thermostat tests bad, the replacement is a manageable DIY job but requires removing the evaporator assembly in some models. If the wiring and components test fine, the main control board is likely at fault, and that diagnosis requires board-level testing. TruePro's $59 diagnostic fee is credited toward the repair. We warranty all defrost repairs for 90 days on parts and labor. CA License #51112. Same-day service is often available across LA County, Orange County, and Ventura County. Call 877-378-3111. Use code NEW15 for 15% off labor if you are a first-time customer.
Estimated Repair Cost
| Option | Estimated Cost |
|---|---|
| DIY (parts only) | $30 - $80 |
| Professional repair | $180 - $380 |
DIY cost covers a defrost heater or bi-metal thermostat. Professional range includes diagnosis, parts, and labor. Board replacement pushes the total to $400-$550.
See full refrigerator repair cost breakdown βLG Refrigerator Er dH β FAQ
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