LG Air Conditioner Error Code 179

Error code 179 indicates a failure of the Sub3 constant speed compressor 2 to operate. The fault is associated with one of three conditions: mechanical locking of the compressor, leakage through a check valve, or dielectric breakdown of the compressor motor windings. This code appears on multi-compressor LG systems and requires hands-on electrical and mechanical diagnostics to resolve.

Yes, this error can indicate serious electrical and mechanical hazards. Dielectric breakdown of the compressor motor windings means insulation has failed, which creates a risk of electrical shorts and potential arc faults. A mechanically locked compressor can also draw dangerously high current. The system should not be repeatedly restarted until the root cause is identified and corrected by a qualified technician.

Resetting the unit may temporarily clear the error code, but the fault will return if the underlying problem is not fixed. Because the three causes associated with error 179, compressor lockup, check valve leakage, and winding insulation failure, are all physical or electrical failures rather than control glitches, a reset will not resolve them. Repeated restart attempts without diagnosis can worsen compressor damage or increase the risk of electrical faults.

Most of the diagnostic and repair steps for error 179 are not suitable for DIY repair. Measuring insulation resistance requires a megohmmeter, testing the magnetic switch involves live electrical components, and any work on the refrigerant circuit requires EPA certification. A licensed HVAC technician should perform these diagnostics. Homeowners can visually check for obvious wiring damage, but should not attempt compressor or refrigerant work.

Repair costs vary significantly depending on the root cause. Replacing a failed check valve typically runs in the range of $150 to $400 including labor. Compressor replacement on a commercial multi-zone system is considerably more expensive, often ranging from $800 to $2,500 or more depending on the unit size and compressor model. Diagnostic labor alone can range from $75 to $200 before any parts are factored in.