Mitsubishi Mini Split Error Code UA: How to Fix It

Medium 30-60 minutes Medium Severity Verified June 2026
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Error Code
UA
Brand
Mitsubishi
Product Type
mini_split
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30-60 minutes
Error code UA on your Mitsubishi mini split indicates a problem with the outdoor unit's main control board (PCB) EEPROM. This usually means the board has corrupted memory or a hardware fault, which may require resetting or replacing the board.
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Tools You'll Need

How to Fix Error Code UA

  1. Power Cycle the System

    Always disconnect power before touching any electrical components to avoid shock.

  2. Check for Loose Connections

    Wait at least 5 minutes after power-off for capacitors to discharge.

  3. Reset the PCB EEPROM

    Use insulated tools to avoid shorting other components.

  4. Test the PCB

    High voltage present. Only perform if you are comfortable and have proper safety gear.

  5. Replace the Outdoor PCB

    Work carefully with polarized connectors; incorrect installation may damage the new board.

Parts You May Need

Outdoor unit main control board (PCB)
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Outdoor unit main control board (PCB)
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Outdoor unit main control board (PCB)
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Outdoor unit main control board (PCB)
Check Price on Amazon
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When to Call a Professional

If power cycling and checking connections don't resolve the error, call a licensed HVAC technician. PCB replacement requires advanced electrical knowledge and matching the correct board to your model.

Frequently Asked Questions

Can I fix error UA by just cleaning the unit?
No. UA is an electronics error related to the PCB, not dirt or airflow. Cleaning will not fix it.
Will error UA cause the mini split to stop working completely?
Yes, typically the outdoor unit will not operate, and the indoor unit may show UA on the display or remote.
How much does a replacement PCB cost for a Mitsubishi mini split?
Prices range from $200 to $600 depending on the model. Always verify compatibility with your unit's serial number.
Is it safe to replace the PCB myself?
If you have experience with high-voltage electronics and follow safety precautions, it is possible. Otherwise, hire a professional.
Can a power surge cause error UA?
Yes. Power surges can corrupt the EEPROM. Using a surge protector can help prevent this.

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