LG Air Conditioner Error Code 79

Error code 79 on an LG air conditioner indicates a fan starting failure caused by an initial position sensing failure in the fan motor. The system checks the rotor's position before spinning the motor, and if that check fails, the unit shuts down and displays this code. It points to a problem with the fan motor assembly, its internal sensors, the wiring harness, or the control board.

No. When error code 79 is active, the unit has already shut down the fan motor to protect the system from damage caused by incorrect motor operation. Attempting to bypass or repeatedly restart the unit without addressing the underlying fault can worsen motor damage or create an electrical hazard. The unit should remain off until the fault is diagnosed and repaired.

A power reset may temporarily clear the error and allow a restart attempt, but if the underlying fault in the fan motor, position sensor, or wiring is still present, the code will return immediately or shortly after startup. Resetting alone does not fix the mechanical or electrical issue causing the fault. A proper diagnosis and repair are required to permanently resolve the error.

Basic checks like inspecting for debris blocking the fan blade or verifying wiring connections are within reach for a knowledgeable DIYer. However, properly diagnosing this error requires measuring motor phase resistance (16.8Ω ±5% at 75°C) and insulation resistance (over 100MΩ) with appropriate test equipment. Motor or control board replacement is best handled by a qualified technician.

Repair costs vary depending on the root cause. A wiring harness repair or connector cleaning is typically the least expensive fix, often in the range of $75 to $150 in labor. Fan motor replacement generally runs between $150 and $400 including parts and labor, depending on the specific unit. Control board replacement tends to be the most expensive option, often ranging from $250 to $600 or more.