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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.

UL

Abnormal Low Pressure

Mitsubishi Electric · R410A Systems

What does UL mean?

The system has detected abnormally low refrigerant pressure. This typically indicates a refrigerant leak or insufficient charge, which can lead to poor cooling/heating performance and potential compressor damage.

Common Causes

  • Abnormally low system pressure detected.
  • Refrigerant undercharge.
  • Restriction in the low-pressure side.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Measure system low-side pressure using manifold gauges.

  2. 2

    Perform a thorough leak detection test on the entire refrigerant circuit, starting from accessible joints and connections.

  3. 3

    Verify refrigerant charge level — if low, recover, evacuate, and recharge to the nameplate capacity.

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

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Source: Mitsubishi Electric R410A Systems
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