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E3 / Indoor & Outdoor Red LEDs 2 flashes

Error E3 / Indoor and Outdoor Red LEDs Flashes Twice — Outdoor/Indoor communication error

Mitsubishi Heavy Industries · Air Conditioners

What does E3 / Indoor & Outdoor Red LEDs 2 flashes mean?

When both the indoor and outdoor unit's red LEDs flash twice, it signals a communication error between the outdoor and indoor units. This prevents the system from operating correctly.

Common Causes

  • Outdoor/Indoor communication error

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Turn off the main power to the entire air conditioning system for 1-2 minutes, then restart it.

  2. 2

    Check the communication wiring between the indoor and outdoor units for any loose connections or damage.

  3. 3

    Ensure that all communication wires are correctly installed and not reversed.

  4. 4

    If the error persists after checking connections and power cycling, a technician should inspect the control boards.

Browse all codes in this manual (110)
Verified technical data. Last updated: April 2026

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01Power source faulty — RUN LED OFF, TIMER LED flashes 1 time05Wired remote control wiring error — RUN LED OFF, TIMER LED flashes 5 times35Cooling high pressure control activated — RUN LED flashes 3 times, TIMER LED flashes 5 times
Source: Mitsubishi Heavy Industries Air Conditioners
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