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ErrorLib — Industrial Fault Code Library

Disclaimer: ErrorLib is an independent technical reference tool. While we aim for accuracy, always verify with the manufacturer’s official service manuals before performing maintenance on industrial equipment. ErrorLib is not affiliated with the brands listed.

F4

49C Connector Open

Mitsubishi Electric · R410A Systems

What does F4 mean?

The 49C connector on the outdoor unit's PCB is detected as open or disconnected. This indicates a break in a circuit, likely related to a current transformer or a thermal protector within the outdoor unit.

Common Causes

  • Open circuit detected at the 49C connector.
  • Wiring issue or disconnection at the 49C thermistor.
  • Faulty 49C temperature sensor.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Inspect the 49C connector on the outdoor unit PCB — verify it is securely seated and free from corrosion.

  2. 2

    Check the continuity of the wiring connected to the 49C connector using a multimeter.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

E0Transmitting/Receiving Signal ErrorE112Auto Addressing Conflict / Factory Address Setting ErrorE14Master/Slave System Configuration Error
Source: Mitsubishi Electric R410A Systems
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