LG Air Conditioner Error Code 109

Error code 109 means the high pressure switch in the sub1 outdoor unit detected an excessive rise in refrigerant pressure and shut the compressor off as a safety measure. This protects the compressor and refrigerant lines from damage caused by dangerously elevated pressure. The system will not resume normal operation until the underlying cause is identified and resolved.

No. The system has already shut the compressor off as a protective measure, and attempting to override or ignore this error risks serious mechanical damage to the compressor and potentially rupturing refrigerant lines. Do not attempt to bypass the high pressure switch. Leave the unit off until the fault is properly diagnosed and repaired.

Repair costs vary widely depending on the cause. A simple connector reseating or coil cleaning service may cost between $75 and $200 for a diagnostic visit and labor. Replacing an outdoor fan motor typically runs $150 to $400 including parts and labor. Refrigerant correction or a high pressure switch replacement can add $100 to $350 or more depending on refrigerant type, regional pricing, and labor rates.

Some causes, like a loose connector on the PCB or a dirty condenser coil, can be addressed by a knowledgeable homeowner. However, diagnosing refrigerant pressure levels, correcting refrigerant charge, and replacing components like the high pressure switch or outdoor fan motor require proper tools and training. Any work involving refrigerant handling must be performed by a certified technician.

A power reset may temporarily clear the error and allow the system to restart, but if the root cause such as a blocked coil, failed fan, or overcharge condition is still present, the high pressure switch will trip again and the error will return. A reset is useful for ruling out a transient fault, but it is not a fix and the system should be fully inspected before relying on it for continuous operation.