Samsung Air Conditioner Error Code P424

P424 indicates that the outdoor unit Electronic Expansion Valve (EEV) failed its close self-diagnosis routine three consecutive times. The outdoor control board commands the EEV to close and checks for confirmation, but the expected response was not detected. This points to a fault in the EEV coil, the valve body itself, the wiring harness, or the outdoor PCB.

It is not advisable to continue operating the unit with this fault active. An EEV that cannot close properly can allow uncontrolled refrigerant flow, which may stress the compressor or cause system inefficiency. Samsung's diagnostic system flags this after three failures specifically to prevent potential damage, so the system should remain off until the fault is resolved.

Repair costs vary depending on the root cause. EEV coil replacement is generally the least expensive component fix, while full EEV valve assembly replacement or outdoor PCB replacement will cost more. Including labor, total repair costs can range from around $150 to $600 or more depending on the specific part required, local labor rates, and whether refrigerant recovery or recharge is needed.

Most of the causes behind P424 require access to the outdoor unit's refrigerant components or control board, which should be handled by a licensed HVAC technician. A knowledgeable DIYer can inspect the EEV wiring harness and connector for obvious damage or corrosion, but coil testing, valve replacement, and PCB diagnosis typically require specialized tools and refrigerant handling certification.

A power reset may temporarily clear the fault code, but if the underlying problem with the EEV or its wiring persists, the error will return during the next self-diagnostic cycle. Because P424 represents a third-occurrence failure, the fault is likely persistent rather than intermittent. A reset alone is not a repair and should not be relied upon as a solution.