Mitsubishi Mini-Split Error Code U1: How to Fix It

Medium 30-60 minutes High Severity Verified June 2026
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Error Code
U1
Brand
Mitsubishi
Product Type
mini_split
Severity
High
DIY Difficulty
Medium
Estimated Fix Time
30-60 minutes
Error code U1 on your Mitsubishi mini-split means the high pressure switch has tripped, shutting down the system to prevent damage. This typically occurs due to a dirty condenser coil, faulty fan motor, or refrigerant issues. Follow the steps below to diagnose and resolve the problem safely.
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Tools You'll Need

How to Fix Error Code U1

  1. Power Off the Unit

    Always disconnect power before servicing electrical components. High voltage can cause injury or death.

  2. Clean the Outdoor Condenser Coil

  3. Check the Condenser Fan Motor

    Do not insert fingers or tools into the fan while it is powered.

  4. Inspect Air Filters and Indoor Unit

  5. Reset the Error Code

Parts You May Need

Condenser fan motor
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High pressure switch
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Condenser fan motor
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High pressure switch
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Condenser fan motor
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High pressure switch
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Condenser fan motor
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High pressure switch
Check Price on Amazon
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When to Call a Professional

If the error persists after cleaning the condenser and checking the fan, call a licensed HVAC technician. Issues like a faulty compressor, restricted refrigerant circuit, or failed high pressure switch require specialized tools and knowledge.

Frequently Asked Questions

What does Mitsubishi mini-split error code U1 mean?
U1 indicates a high pressure cutout, meaning the high pressure switch has opened to protect the compressor from excessive pressure.
Can I fix error U1 myself?
You can try cleaning the condenser coil and checking the fan motor. If the error returns, you likely need a professional to diagnose refrigerant or compressor issues.
How do I reset error code U1 on a Mitsubishi mini-split?
Turn off the unit at the breaker for 10 minutes, then turn it back on. On the remote, press and hold the 'Check' button for 3 seconds to clear the code.
What causes high pressure in a mini-split?
Common causes include dirty condenser coil, faulty condenser fan, blocked indoor airflow, overcharged refrigerant, or a non-condensable gas in the system.
Is it safe to run the mini-split with error U1?
No. The system shuts down to prevent compressor damage. Do not attempt to bypass the safety switch. Address the underlying issue before restarting.

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