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Error code reference

LG Refrigerator Error Code r dH

Refrigerator defrosting error

LG codesLG refrigerator codes

Refrigerator defrosting error - defrosting sensor does not reach over 40°F (5°C) after 50 minutes of defrosting; caused by temperature fuse disconnection, heater disconnection, drain jam, or poor relay for heater.

First step from the service manual

Check the door gasket, then check the defrost control part (Fuse-M and Defrost Heater resistance).

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What r dH means on a LG refrigerator

The r dH error code on an LG refrigerator indicates a refrigerator compartment defrost failure. Specifically, the defrost sensor fails to reach a temperature above 40°F (5°C) within 50 minutes of the defrost cycle initiating. The refrigerator's control board monitors the defrost sensor continuously during the defrost cycle, and when that threshold is not met within the allotted time, it triggers this fault code. The defrost system involves several interdependent components: the defrost heater, the thermal fuse (Fuse-M), the defrost sensor, and the relay that controls heater activation.

The most common hardware causes include a blown thermal fuse, an open-circuit defrost heater, a jammed or frozen drain that prevents heat from dissipating properly, or a faulty relay that prevents power from reaching the heater at all. A failed thermal fuse is a protective device that opens permanently when it detects excessive heat, cutting power to the heater circuit entirely. A disconnected or burned-out heater will produce the same result: no heat generated during the defrost cycle, so evaporator frost never melts and the sensor never climbs above the 40°F threshold.

Diagnostics begin with inspecting the door gasket for any tears or poor seals, since excessive frost buildup from warm air intrusion can overwhelm the defrost system. From there, the defrost control components should be tested: check the Fuse-M for continuity and measure the defrost heater resistance to confirm it is within specification. A heater showing infinite resistance (open circuit) confirms it has failed and requires replacement.

Source: manufacturer service documentation.

Common causes of r dH

  1. 01

    Blown Thermal Fuse (Fuse-M)

    Part replacement

    The thermal fuse is a one-time safety device that permanently opens if it detects excess heat, cutting the defrost heater circuit. Test it with a multimeter for continuity; no continuity confirms it has blown and must be replaced.

  2. 02

    Failed Defrost Heater

    Part replacement

    The defrost heater generates the heat needed to melt frost off the evaporator coils. Measure its resistance with a multimeter; an open circuit reading (infinite resistance) indicates the heater element has burned out.

  3. 03

    Faulty Heater Relay

    Part replacement

    The relay on the control board is responsible for switching power to the defrost heater. If the relay fails to close, the heater never receives power even if the heater itself is functional.

  4. 04

    Jammed or Frozen Drain

    Wiring / connection

    A blocked defrost drain can cause ice to accumulate around the drain and evaporator area, preventing heat from distributing properly during the defrost cycle. Inspect the drain opening for ice blockages or debris.

  5. 05

    Damaged or Poorly Sealing Door Gasket

    Part replacement

    A torn or warped door gasket allows warm, humid air into the refrigerator compartment, causing excessive frost buildup that the defrost cycle cannot fully address within its 50-minute window. Inspect the gasket along its entire perimeter for gaps, tears, or areas that do not seal flush against the cabinet.

See the test procedure for each cause

Frequently asked questions about r dH

What does r dH mean on a LG refrigerator?
The r dH code means the refrigerator compartment defrost cycle has failed. The defrost sensor did not detect a temperature rise above 40°F (5°C) within 50 minutes of the defrost cycle starting. This points to a problem in the defrost circuit, most commonly a blown thermal fuse, a failed defrost heater, a bad heater relay, or a clogged drain.
Can I fix the r dH error myself?
Some steps are DIY-friendly, such as inspecting and cleaning a blocked defrost drain or checking the door gasket for damage. Testing the thermal fuse and defrost heater for continuity and resistance requires a multimeter and basic familiarity with appliance wiring. Replacing the heater or fuse is a moderate-difficulty repair, but if the issue is a faulty relay on the control board, a technician is typically better suited to handle that diagnosis and repair.
Is it safe to keep using my refrigerator while this error is showing?
Continued use with an active r dH error is not recommended for long-term food safety. Without a functioning defrost cycle, frost will accumulate on the evaporator coils until airflow is blocked, which causes the refrigerator to lose cooling ability. Food temperatures may rise into unsafe ranges over time, so the issue should be addressed promptly.
Will resetting my LG refrigerator clear the r dH error?
A reset may temporarily clear the displayed code, but it will not fix the underlying hardware problem. The error will return the next time the defrost cycle runs and the sensor again fails to reach 40°F within 50 minutes. The root cause, whether a blown fuse, failed heater, bad relay, or blocked drain, must be diagnosed and corrected for the error to clear permanently.
How much does it cost to repair an r dH defrost error on an LG refrigerator?
Repair costs vary depending on which component has failed. Replacing a thermal fuse or defrost heater is generally on the lower end of the cost range, typically between $80 and $200 including parts and labor. A control board relay issue or full board replacement can push costs higher, often in the $150 to $400 range. Getting a specific diagnosis before authorizing parts replacement is the best way to avoid unnecessary expense.

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