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Upper lamp blinks 4-time blink 2.5-second OFF

Upper lamp blinking four times — Indoor control system memory error

Mitsubishi Electric · Air Conditioning

What does Upper lamp blinks 4-time blink 2.5-second OFF mean?

The system cannot properly read data from the non-volatile memory of the indoor electronic control P.C. board. The unit will not operate.

Common Causes

  • Corrupted data in indoor control board memory
  • Faulty indoor electronic control P.C. board

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Replace the indoor electronic control P.C. board.

  2. 2

    Ensure the unit's power supply is stable.

Browse all codes in this manual (170)
Verified technical data. Last updated: April 2026

Related Faults

0.5-second ON / 0.5-second OFF blinkUpper lamp blinks 0.5-second ON/OFF - Miswiring or serial signal error00Normal operation - No error codes1 beep during error display mode1 beep during error display mode - Unit has an error (different code)
Source: Mitsubishi Electric Air Conditioning
Open Manual (Page 38)Search more codes in this manual