LG Air Conditioner Error Code 100

Error code 100 means the system shut down because the discharge temperature of constant speed compressor 1 in the sub1 outdoor unit exceeded a safe limit. This is a protective fault designed to prevent compressor damage. The system will not restart until the underlying cause is identified and corrected. A technician should begin diagnosis by checking the refrigerant charge.

No, you should not attempt to bypass or ignore this error. The system shuts down automatically to protect the compressor from damage caused by overheating. Continuing to operate the unit in this condition could result in complete compressor failure, which is a much more costly repair than addressing the root cause early.

A power reset may temporarily clear the fault and allow the unit to restart, but if the underlying cause has not been resolved, the discharge temperature will rise again and the system will shut down and re-display the error. Resetting without diagnosis risks repeated compressor overheating and can accelerate component wear. The fault should be properly diagnosed before attempting a reset.

Some contributing factors, such as a dirty condenser coil or blocked airflow around the outdoor unit, can be addressed without specialized tools. However, checking refrigerant levels requires certified technician equipment, and handling refrigerants legally requires EPA Section 608 certification. If airflow and coil cleanliness check out, contact a licensed HVAC technician to diagnose refrigerant or compressor issues.

Repair costs vary widely depending on the cause. A refrigerant recharge and leak repair can range from $200 to $800 or more depending on refrigerant type and leak location. Condenser coil cleaning is typically $75 to $200. Fan motor replacement generally falls in the $150 to $400 range. Compressor replacement is the most expensive outcome, often ranging from $1,000 to $2,500 or higher for commercial multi-zone systems.