Error E3 / Indoor Red LED Flashes Twice — Outdoor unit PCB or inverter fault

What does E3 / Indoor Red LED 2 flashes (Outdoor Red LED Off) mean?

Error E3, with the indoor unit's red LED flashing twice and the outdoor unit's red LED staying off, suggests a failure in the outdoor unit's control PCB or faulty inverter components.

• Outdoor unit control PCB failure
• Inverter parts faulty
• The outdoor power unit failure (where indoor/outdoor power supplies are separated)
• Indoor/outdoor communication error
• A and B wiring reversed after power on

Click steps to track your progress.

1. 1

   Perform a power cycle by switching off the system's main power for several minutes, then turning it back on.

2. 2

   Listen for any unusual sounds from the outdoor unit after restart.

3. 3

   Verify that the A and B communication wires are connected correctly and not reversed.

4. 4

   This type of fault usually requires specialized diagnostic tools and expertise.

5. 5

   Contact a certified Mitsubishi Heavy Industries technician for inspection and repair of the outdoor unit PCB or inverter parts.