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POWER lamp 0.5-second flash - Normal Troubleshooting

POWER lamp flashes ON and OFF at 0.5-second intervals — Indoor/outdoor unit miswiring or serial signal trouble (normal troubleshooting)

Mitsubishi Electric · MSZ-FH Air Conditioners

What does POWER lamp 0.5-second flash - Normal Troubleshooting mean?

During normal operation troubleshooting, the indoor unit's POWER lamp flashes ON and OFF at 0.5-second intervals. This typically signifies miswiring or a serial signal communication problem between the indoor and outdoor units.

Common Causes

  • Miswiring between indoor/outdoor unit
  • Serial signal communication error

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Refer to 10-6. 'How to check miswiring and serial signal error' (further details may require an installer).

  2. 2

    Check the indoor/outdoor connecting wire for proper connection and ensure it is not damaged.

  3. 3

    Ensure the power supply is correctly connected to both indoor and outdoor units.

Browse all codes in this manual (41)
Verified technical data. Last updated: April 2026

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Source: Mitsubishi Electric MSZ-FH Air Conditioners
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