LG Refrigerator Error Code FZ-DEF-HEATER Error

The FZ-DEF-HEATER error indicates a fault in the freezer compartment's defrost heating system. The control board has detected an issue such as a heater disconnection, short circuit, contact error, or blown thermal fuse. This system is responsible for periodically melting frost off the evaporator coils to keep the refrigerator cooling correctly. Diagnosis requires resistance testing at the main PCB connectors CN70 and CN71.

Continued use with this error active is not recommended for long periods. Without a functioning defrost heater, frost will accumulate on the evaporator coils, eventually blocking airflow and causing the refrigerator and freezer compartments to lose cooling ability. Food safety can be compromised if temperatures rise above safe levels. Address the error as soon as possible to avoid food spoilage.

A power reset may temporarily clear the error code from the display, but it will not resolve the underlying electrical fault in the defrost heater circuit. The code will return once the control board runs its diagnostics again. A physical component failure such as a blown thermal fuse or broken heater element must be repaired or replaced before the error will clear permanently.

A knowledgeable DIYer can perform the initial resistance test by disconnecting CN70 and CN71 from the main PCB and measuring between the White and Orange wires, looking for a reading of 63 or 230 ohms within 7% tolerance. If the thermal fuse or heater element is confirmed faulty, replacing these parts requires accessing the freezer evaporator panel, which involves removing shelving and covers. If you are not comfortable working with refrigerator internals or interpreting electrical resistance readings, a qualified technician is recommended.

Repair costs depend on which component has failed. A thermal fuse replacement is typically the least expensive repair, with parts generally ranging from $5 to $25 and labor adding $75 to $150 depending on your area. A defrost heater element replacement usually costs between $20 and $80 for the part, plus labor. If the main PCB is involved, costs can rise considerably higher.