LG Air Conditioner Error Code 154

Error code 154 indicates that the high-side refrigerant pressure in the sub3 outdoor unit rose to an unsafe level, causing the high pressure switch to open and shut down the compressor. This is a protective fault designed to prevent compressor and system damage. The code points to either a genuine overpressure condition in the refrigerant circuit or a wiring issue with the high pressure switch connector at the PCB.

No, you should not attempt to bypass or continue operating the system with this fault active. The high pressure switch tripped because pressure reached a potentially dangerous level, and running the compressor under those conditions risks serious damage to the compressor, refrigerant lines, and other components. Leave the unit off until the root cause has been identified and corrected.

Repair costs vary widely depending on the cause. Cleaning a blocked condenser coil is generally a low-cost service call in the range of $75 to $200. Replacing a condenser fan motor or high pressure switch typically falls in the $150 to $450 range including parts and labor. If the system requires refrigerant recovery, recharge, or compressor replacement, costs can rise significantly higher, so an accurate diagnosis is important before committing to repairs.

Start by checking that the high pressure switch connector is fully seated and undamaged at the outdoor unit PCB. If the connection is secure, inspect the condenser coil for blockage and verify the condenser fan is operating. If those checks pass, a certified HVAC technician should connect manifold gauges to measure actual high-side pressure and determine whether refrigerant charge, contamination, or a failed switch is responsible.

A power reset may temporarily clear the code and allow the system to restart, but if the underlying cause of high pressure has not been addressed, the fault will return and the compressor will shut down again. Resetting without diagnosing the problem is not a repair. The issue needs to be fully resolved to prevent the code from recurring.