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Error code reference

Samsung Air Conditioner Error Code P406

Momentary power failure

Samsung codesSamsung air conditioner codes

Momentary power failure – temporary stop of compressor as protection control (not a defect).

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What P406 means on a Samsung air conditioner

P406 on a Samsung air conditioner is a protective response to a momentary power failure. When the unit detects a brief interruption in the incoming power supply, the control board initiates a temporary compressor shutdown to prevent mechanical damage. This is a deliberate, built-in protection function, not a defect or component failure. The compressor requires stable voltage to operate safely, and even a short power fluctuation can create conditions that risk damage to the compressor motor or refrigerant circuit if the compressor attempts to restart immediately.

The protection logic prevents the compressor from cycling back on too quickly after the power interruption. Rapid restart attempts after a power dip can cause the compressor to start under high head pressure, which can damage the motor windings or internal components. By holding the compressor off for a defined delay period, the system allows pressures to equalize and incoming power to stabilize before resuming normal operation.

In most cases, P406 will clear automatically once the unit completes its protection delay and confirms stable power. If the code appears repeatedly or the unit does not resume normal operation after several minutes, the underlying power supply quality should be investigated. Frequent occurrences suggest grid instability, an overloaded circuit, a failing disconnect or breaker, or inadequate wiring causing voltage drops at the unit.

Source: manufacturer service documentation.

Common causes of P406

  1. 01

    Utility grid voltage fluctuation

    Wiring / connection

    Brief dips or spikes in the power supplied by the utility grid are the most common trigger for P406. Check whether other appliances in the home experienced a flicker or interruption at the same time.

  2. 02

    Overloaded or undersized circuit breaker

    Wiring / connection

    If the air conditioner shares a circuit with other high-draw appliances, or if the breaker is rated below the unit's requirements, momentary voltage drops can occur under load. Verify the breaker rating matches the unit's specifications on the nameplate.

  3. 03

    Loose or corroded wiring connections

    Wiring / connection

    Loose connections at the disconnect box, breaker panel, or unit terminals can cause intermittent power interruptions that trigger P406. Inspect all connection points for corrosion, heat discoloration, or physical looseness.

  4. 04

    Failing disconnect switch or contactor

    Part replacement

    A worn disconnect switch or contactor that is beginning to fail can cause momentary power interruptions to the unit. If P406 occurs frequently with no obvious grid issue, these components should be tested for proper contact integrity.

  5. 05

    Undersized or degraded supply wiring

    Part replacement

    Wiring that is too small for the unit's amperage draw or that has degraded insulation can produce voltage drops under load, mimicking a momentary power failure. A licensed electrician should measure voltage at the unit terminals during operation to confirm.

See the test procedure for each cause

Frequently asked questions about P406

What does P406 mean on a Samsung air conditioner?
P406 indicates that the unit detected a momentary power failure and temporarily stopped the compressor as a protective measure. This is a built-in safety function designed to prevent compressor damage from unstable power conditions. It is not classified as a defect. The unit should resume normal operation automatically once power stabilizes and the protection delay completes.
Will P406 clear on its own, or do I need to reset the unit?
In most cases, P406 will clear automatically after the compressor protection delay expires and the unit confirms that incoming power is stable. A manual reset is generally not required for a single occurrence. If the code persists or returns frequently, the power supply to the unit should be inspected rather than relying on repeated resets.
Is it safe to continue using my Samsung air conditioner after a P406 code?
A single P406 event is not a safety concern and the unit is designed to handle this situation automatically. However, if P406 appears repeatedly, continued operation under unstable power conditions could eventually stress electrical components. Investigating and correcting the power supply issue is advisable before continuing heavy use.
How do I fix a P406 error on my Samsung air conditioner?
Start by checking whether the power interruption was isolated to the air conditioner or affected other devices in the home. Inspect the dedicated circuit breaker, disconnect box, and wiring connections for any signs of looseness, corrosion, or overloading. If the code recurs frequently, have a licensed electrician measure voltage at the unit terminals under load to confirm the supply meets the unit's requirements.
How much does it cost to repair a P406 error on a Samsung air conditioner?
If the cause is a utility grid fluctuation or a loose wiring connection, the cost may be minimal, ranging from nothing to roughly $50 to $150 for an electrician's service call to tighten connections. If a failing disconnect switch, contactor, or circuit breaker replacement is needed, parts and labor typically range from $100 to $400 depending on the component and local labor rates. Full wiring upgrades for undersized circuits can range considerably higher.

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