LG Air Conditioner Error Code 146

Error code 146 on an LG air conditioner indicates that the Sub2 outdoor unit has experienced an excessive drop in low-side (suction) pressure, causing the compressor to shut down as a protective measure. This applies to three-unit outdoor configurations. The system stops the compressor automatically to prevent internal damage from operating at unsafe pressure levels. A technician needs to identify and correct the cause before the unit can be restarted.

The system has already taken action by shutting off the compressor in the Sub2 outdoor unit, which is the correct protective response. You should not attempt to force the system to run while this fault is active, as operating a compressor under very low suction pressure can cause severe internal damage including loss of lubrication and mechanical failure. Leave the unit off until the fault has been properly diagnosed and resolved.

Repair costs vary significantly depending on the cause. If a service valve simply needs to be opened, the cost may only be a diagnostic service call fee, typically in the range of $75 to $150. If refrigerant has leaked and the system needs leak repair and recharge, costs can range from $300 to $700 or more depending on refrigerant type and labor. Component replacements such as a filter drier or expansion valve add parts and labor costs on top of that.

The first step, checking whether the service valves on the Sub2 outdoor unit are fully open, can be done without specialized tools and is worth verifying before calling for service. However, if the valves are open and the error persists, diagnosing refrigerant levels, sensor function, or component restrictions requires manifold gauges and refrigerant handling certification. Most homeowners should contact a licensed HVAC technician for anything beyond a basic valve check.

A power reset may temporarily clear the fault display, but the error will almost certainly return quickly if the underlying cause has not been addressed. The low pressure condition that triggered the shutdown will still be present, and the compressor protection logic will activate again once the unit attempts to restart. A reset is not a repair and should only be done after the root cause has been identified and corrected.