LG HVAC Error Code 28

Error code 28 on an LG HVAC system means the inverter DC link voltage is too low. The inverter circuit has detected that it cannot build up sufficient DC bus voltage to safely operate the variable-speed compressor. This is a protective shutdown to prevent compressor and electronics damage. The fault is most often caused by supply voltage falling outside the required 193 to 253V AC range.

No. Error code 28 is a protective fault that causes the system to shut down automatically, so in most cases the unit will not continue operating while this code is active. Attempting to force the system to run with inadequate DC link voltage can cause permanent damage to the compressor and inverter components. Address the underlying cause before resuming normal operation.

Repair costs vary depending on the cause. If the fix involves tightening connections or replacing a breaker, costs are typically in the range of $75 to $300 including labor. If the inverter PCB has failed and requires replacement, parts and labor costs can range from $400 to $900 or more depending on the specific unit and local labor rates.

Checking the incoming AC supply voltage is something a knowledgeable DIYer with a multimeter can do safely at the outdoor unit's terminal block. However, diagnosing and replacing an inverter PCB involves working with high-voltage DC bus capacitors that can hold a dangerous charge even after power is removed. PCB-level work should be performed by a qualified HVAC technician.

A power reset may temporarily clear the fault display, but the error will return if the underlying cause has not been corrected. If the AC supply voltage is still out of the 193 to 253V AC range, or if the inverter PCB has failed, the code will reappear upon restart. Resetting without diagnosing the root cause is not a solution.