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: March 2026

Related Faults

Source: Mitsubishi Electric R410A Systems