U5 (4230) - Heat sink temperature trouble

What does U5 mean?

The heat sink, which helps dissipate heat from power components in the Mitsubishi Electric PUMY Air Conditioner, is experiencing a temperature issue (likely overheating). The system will stop operating.

• Overheating of the power module or related components
• Poor airflow to the heat sink due to obstructions or dirt
• Faulty temperature sensor monitoring the heat sink
• Malfunctioning fan failing to cool the heat sink

Click steps to track your progress.

1. 1

   Note the error code displayed on the remote controller or outdoor unit.

2. 2

   Ensure the outdoor unit has adequate ventilation and is not obstructed by debris, leaves, or other blockages.

3. 3

   Power off the Mitsubishi Electric PUMY Air Conditioner system at the main electrical breaker.

4. 4

   Wait for at least 30 seconds, then restore power to the system.

5. 5

   If the error persists, contact a qualified service technician to inspect the heat sink and related components.