LG Hvac Error Code 24

Error code 24 on an LG HVAC system indicates that the high or low pressure switch has opened, interrupting normal operation as a protective measure. The low pressure switch trips when system pressure falls to 14 PSI, while the high pressure switch trips at 600 PSI. These switches monitor refrigerant circuit pressure continuously and will open the circuit to prevent compressor damage when pressures move outside safe operating limits. The system shuts down rather than allowing the compressor to run under conditions that could cause mechanical failure or refrigerant circuit damage.

For Flex Multi systems, the first diagnostic priority is verifying that indoor unit wiring has not been reversed or incorrectly connected. If the wiring is switched, refrigerant may be directed to the wrong coil while the indoor unit fan remains off. Without airflow across the active coil, heat exchange cannot occur, which causes refrigerant pressure to drop rapidly and trip the low pressure switch at 14 PSI. This wiring error is a common source of nuisance low pressure faults and should be ruled out before proceeding to refrigerant quantity or component-level diagnostics.

Beyond wiring issues, legitimate low pressure conditions can result from refrigerant leaks, blocked or restricted metering devices, and failed or stuck expansion valves. High pressure faults at 600 PSI typically point to a blocked condenser, failed condenser fan, overcharged refrigerant circuit, or non-condensable gases in the system. Accurate diagnosis requires manifold gauge readings taken at the service ports to determine whether the fault is on the high side or low side, and whether pressures are consistent with the corresponding fault condition.