LG Air Conditioner Error Code 145

Error code 145 on an LG air conditioner indicates that the high-side refrigerant pressure in the Sub2 outdoor unit has risen excessively, causing the system to shut down that unit's compressor as a safety measure. This occurs in three-unit outdoor configurations where the Sub2 unit is one of two subordinate units. The fault protects the compressor and refrigerant circuit from damage caused by extreme pressure conditions. A technician must diagnose the root cause before the system can resume normal operation.

The error itself represents the system working correctly to prevent a dangerous situation. Excessively high refrigerant pressure can rupture lines, damage the compressor, or cause refrigerant leaks if left unchecked. The compressor shutdown triggered by this fault protects the equipment and prevents a more serious failure. A qualified HVAC technician should evaluate and resolve the cause before the system is returned to service.

Repair costs vary widely depending on the cause. If the issue is simply a closed service valve or a dirty condenser coil, the cost may be limited to a service call fee in the range of $75 to $200. If a condenser fan motor needs replacement, parts and labor could total between $150 and $450. If the refrigerant circuit requires evacuation and recharge due to contamination or overcharge, expect costs in the range of $200 to $600 or more depending on refrigerant type and quantity.

Start by checking whether the service valve on the Sub2 outdoor unit is fully open, as a closed valve is the most direct cause of this fault. If the valve is open, inspect the condenser coil for dirt or blockage, confirm the condenser fan is spinning correctly, and have a certified technician check the refrigerant charge with manifold gauges. Do not attempt to restart the system repeatedly without addressing the underlying cause, as doing so risks compressor damage.

Resetting the unit may temporarily clear the fault and allow a restart, but the error will return if the underlying cause is not corrected. If the condition that drove the high pressure, such as a closed service valve or a blocked condenser, is still present, the compressor will shut down again quickly. Repeated resets without a repair can accelerate wear on the compressor. A proper diagnosis and fix must be performed to permanently clear the code.