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Error code reference

Samsung Air Conditioner Error Code P424

Outdoor unit EEV close 3 self diagnosis error.

Samsung codesSamsung air conditioner codes

Outdoor unit EEV close 3 self diagnosis error.

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What P424 means on a Samsung air conditioner

Error code P424 on a Samsung air conditioner indicates an Electronic Expansion Valve (EEV) close self-diagnosis failure on the outdoor unit, specifically a third-occurrence fault. The EEV is a precision refrigerant flow control component that regulates the amount of refrigerant entering the indoor coil or heat exchanger. During its self-diagnostic routine, the outdoor unit controller commands the EEV to close fully and then verifies that the valve has responded correctly. When this confirmation fails for the third consecutive time, the system logs P424 and may halt operation to prevent refrigerant flow irregularities or compressor damage.

The most common root causes include a mechanically seized or stuck valve body, a faulty EEV stepper motor coil, wiring harness faults between the outdoor control board and the EEV, or a failed outdoor PCB that cannot properly drive the valve. EEV coil failures can often be identified by measuring resistance across the coil terminals; an open circuit or significant deviation from the expected resistance range indicates a failed coil. Wiring issues such as loose connectors, corrosion at the harness plug, or a broken wire can also prevent the control signal from reaching the valve.

Because this is a third self-diagnosis failure rather than a first occurrence, intermittent faults are less likely than a persistent mechanical or electrical problem. Technicians should inspect the EEV coil, harness continuity, connector integrity, and outdoor board output signals before condemning any single component. Refrigerant contamination or moisture ingress can also cause the valve needle to seize in position, requiring replacement of the valve assembly.

Source: manufacturer service documentation.

Common causes of P424

  1. 01

    Faulty EEV stepper motor coil

    Part replacement

    The stepper motor coil that drives the expansion valve can fail electrically, preventing the valve from receiving the close command. This can be identified by measuring coil resistance at the EEV connector terminals and checking for an open circuit or out-of-spec reading.

  2. 02

    Mechanically seized EEV valve body

    Part replacement

    Moisture ingress, refrigerant contamination, or debris can cause the valve needle to seize in a fixed position. A seized valve will not respond to control signals regardless of coil or board condition, and typically requires full valve assembly replacement.

  3. 03

    Wiring harness or connector fault

    Wiring / connection

    Corroded, loose, or broken wiring between the outdoor control board and the EEV can interrupt the drive signal. Inspecting the connector pins and testing harness continuity can isolate this issue without replacing any major components.

  4. 04

    Failed outdoor unit PCB

    Part replacement

    If the outdoor control board cannot generate or output the correct drive signal to the EEV stepper motor, the valve will not respond during self-diagnosis. This is typically diagnosed after confirming the EEV coil and wiring are in good condition.

  5. 05

    Refrigerant system contamination

    Part replacement

    Moisture or non-condensables in the refrigerant circuit can freeze or corrode the EEV needle and seat, causing mechanical binding. This condition may also require a full system flush or refrigerant replacement in addition to valve repair.

See the test procedure for each cause

Frequently asked questions about P424

What does P424 mean on a Samsung air conditioner?
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.
Can I fix the P424 error myself?
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.
Is it safe to keep running my air conditioner with a P424 error?
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.
Will resetting my Samsung air conditioner clear the P424 error?
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.
How much does it cost to repair a P424 error on a Samsung air conditioner?
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.

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