LG Air Conditioner Error Code 105

Error code 105 on an LG air conditioner means the fan PCB did not receive a communication signal from the inverter PCB. This is a transmission error between two internal control boards. The unit shuts down because it cannot coordinate fan and compressor operation without that signal. A technician will need to inspect the wiring and boards to resolve it.

No. When error code 105 is active, the unit will typically shut itself down automatically because the fan and inverter boards cannot communicate. Attempting to force the unit to run without resolving the communication fault could result in damage to the compressor or other components. Leave the unit off until the fault is diagnosed and cleared.

If the repair only requires reseating a cable connection, labor costs are typically minimal, often in the range of $75 to $150 for a service call. If a fan PCB replacement is needed, parts and labor combined can range from $200 to $500 or more depending on the model. Inverter PCB replacement is generally more expensive and can push total repair costs higher, making it worth comparing repair cost against unit age and replacement cost.

Some causes of error 105 are accessible to a knowledgeable DIYer, such as reseating a loose transmission cable or power cable connector. However, accessing the inverter and fan PCBs requires opening the unit and working near high-voltage components, which carries serious safety risks. If you are not experienced with appliance electronics, a qualified HVAC technician should perform the diagnosis and repair.

A power reset may temporarily clear the error display, but if the underlying wiring or component fault is still present, the error code will return. Resetting the unit without fixing the root cause, such as a loose cable or failed PCB, will not resolve the problem. A proper diagnosis of the transmission cable, DC 15V power cable, and PCB condition is necessary for a lasting fix.