Mitsubishi Electric All Systems

Mitsubishi Electric Error Code U3

Troubleshooting guide for the Mitsubishi Electric system fault U3.

What It Means

Discharge pipe temperature thermistor open or short circuit fault.

Possible Causes

  • Discharge thermistor open or shorted.
  • Discharge thermistor wiring or connector fault.

Not sure which one it is — or if it's none of these? Try ACLogics today.

Disclaimer: This information is for general reference. Error codes can vary by model and production year. Always refer to your machine's specific manual and the information printed on the unit itself.
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Full Diagnosis

Error detail Discharge thermistor short/open.

All Recorded Causes

Verify Before Replacing Parts

  1. Confirm the exact Mitsubishi Electric model family and default context before acting on a generic code description.
  2. Verify airflow first, then confirm operating pressures and temperature relationship before adjusting charge, since the most likely cause listed above.
  3. Look for restrictions, iced coils, or dirty heat-transfer surfaces that can mimic a charge problem, and separately confirm the next candidate on the list.
  4. After the correction, run the system long enough to confirm the default fault does not return under normal load.

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ACLogics has guided diagnostics for 73 Mitsubishi Electric fault codes and asks the right questions to narrow it down.

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