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6600

6600 Address overlap

Mitsubishi Electric · City Multi Air Conditioning Systems

What does 6600 mean?

This error indicates that two or more units (such as outdoor, indoor, Fresh Master, Lossnay, or remote controllers) within the air conditioning system have been assigned the same address. This prevents proper communication.

Common Causes

  • Duplicated addressing among controllers (outdoor unit, indoor unit, Fresh Master, Lossnay, or remote controller).

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Turn off the power to the entire system at the main circuit breaker.

  2. 2

    Review the address settings for all components in the system (outdoor, indoor, Fresh Master, Lossnay, remote controllers).

  3. 3

    Ensure each component has a unique address assigned according to the installation manual.

  4. 4

    Restore power to the system.

  5. 5

    If the error persists, consult the installation manual for detailed addressing procedures or contact a qualified technician.

Browse all codes in this manual (51)
Verified technical data. Last updated: April 2026

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0403 (Ed)0403 (Ed) Serial communication error1102 <1202> (U2)1102 <1202> (U2) Compressor temperature trouble1302 <1402> (UE)1302 <1402> (UE) High pressure trouble
Source: Mitsubishi Electric City Multi Air Conditioning Systems
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