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Mitsubishi Electric · Heat pumps · Mitsubishi Electric Ecodan PUZ-WM outdoor unit (R32)

U9Overvoltage/undervoltage, input current sensor/L1-phase open, power synchronous signal or PFC/IGBT error (detailed codes 01–20)

Name in the manufacturer's documentation (service manual): Overvoltage/undervoltage, input current sensor/L1-phase open, power synchronous signal or PFC/IGBT error (detailed codes 01–20)[1]

In plain words (editorial)

A power-related error group (overvoltage/undervoltage, input current sensor, phase open, synchronisation, PFC/IGBT) with detailed sub-codes. The service manual lists supply voltage drops, compressor wiring and other causes.

When to call a service technician: The detailed sub-code is read by the installer on the outdoor board.

✎ editorial – written from the cited sources, not a manufacturer statement. Status: draft.

The Polish page has more detail (plain-language explanation, safe checks, guides): Read in Polish →

Sources

Every statement has a footnote to the document and PDF page. “Quote verified” means the quote was found automatically in the text of that page.

  1. [1] Mitsubishi Electric – Service Manual: Air to water heat pump units, outdoor unit PUZ-WM50VHA … PUZ-WM112YAA (OCH727 REVISED EDITION-A, 12/2023) (OCH727A (12/2023)) , p. 27 official manufacturer document quote verified
  2. [2] Mitsubishi Electric – Service Manual: Air to water heat pump units, outdoor unit PUZ-WM50VHA … PUZ-WM112YAA (OCH727 REVISED EDITION-A, 12/2023) (OCH727A (12/2023)) , p. 27 official manufacturer document quote verified to find out the detail history (latest) about u9 error
  3. [3] Mitsubishi Electric – Service Manual: Air to water heat pump units, outdoor unit PUZ-WM50VHA … PUZ-WM112YAA (OCH727 REVISED EDITION-A, 12/2023) (OCH727A (12/2023)) , p. 27 official manufacturer document quote verified decrease in power source voltage,
  4. [4] Mitsubishi Electric – Service Manual: Air to water heat pump units, outdoor unit PUZ-WM50VHA … PUZ-WM112YAA (OCH727 REVISED EDITION-A, 12/2023) (OCH727A (12/2023)) , p. 27 official manufacturer document quote verified disconnection of compressor wiring 2c
  5. [5] Mitsubishi Electric – Service Manual: Air to water heat pump units, outdoor unit PUZ-WM50VHA … PUZ-WM112YAA (OCH727 REVISED EDITION-A, 12/2023) (OCH727A (12/2023)) , p. 27 official manufacturer document quote verified compressor has a ground fault
  6. [6] Mitsubishi Electric – Service Manual: Air to water heat pump units, outdoor unit PUZ-WM50VHA … PUZ-WM112YAA (OCH727 REVISED EDITION-A, 12/2023) (OCH727A (12/2023)) , p. 27 official manufacturer document quote verified distortion of power source voltage,
  7. [7] Mitsubishi Electric – Service Manual: Air to water heat pump units, outdoor unit PUZ-WM50VHA … PUZ-WM112YAA (OCH727 REVISED EDITION-A, 12/2023) (OCH727A (12/2023)) , p. 27 official manufacturer document quote verified defective outdoor power circuit board 4
  8. [8] Mitsubishi Electric – Service Manual: Air to water heat pump units, outdoor unit PUZ-WM50VHA … PUZ-WM112YAA (OCH727 REVISED EDITION-A, 12/2023) (OCH727A (12/2023)) , p. 27 official manufacturer document quote verified 1 check the field facility for the power sup-
  9. [9] Mitsubishi Electric – Service Manual: Air to water heat pump units, outdoor unit PUZ-WM50VHA … PUZ-WM112YAA (OCH727 REVISED EDITION-A, 12/2023) (OCH727A (12/2023)) , p. 27 official manufacturer document quote verified orrect the wiring (u.v.w phase) to
  10. [10] Mitsubishi Electric – Service Manual: Air to water heat pump units, outdoor unit PUZ-WM50VHA … PUZ-WM112YAA (OCH727 REVISED EDITION-A, 12/2023) (OCH727A (12/2023)) , p. 27 official manufacturer document quote verified check compressor for electrical insula-
  11. [11] Mitsubishi Electric – Service Manual: Air to water heat pump units, outdoor unit PUZ-WM50VHA … PUZ-WM112YAA (OCH727 REVISED EDITION-A, 12/2023) (OCH727A (12/2023)) , p. 27 official manufacturer document quote verified 2 check earth wiring
  12. [12] Mitsubishi Electric – Service Manual: Air to water heat pump units, outdoor unit PUZ-WM50VHA … PUZ-WM112YAA (OCH727 REVISED EDITION-A, 12/2023) (OCH727A (12/2023)) , p. 27 official manufacturer document quote verified replace outdoor power circuit board. wm50/60/85