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

U3Open/short circuit of outdoor unit temperature thermistor (TH4, TH33)

Name in the manufacturer's documentation (service manual): Open/short circuit of outdoor unit temperature thermistor (TH4, TH33)[1]

In plain words (editorial)

Open or short circuit of an outdoor unit thermistor (TH4, TH33) – a connector, the thermistor or the controller board.

When to call a service technician: Call the installer.

✎ 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. 25 official manufacturer document quote verified temperature thermistor (TH4, TH33)
  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. 25 official manufacturer document quote verified Check connection of connector (TH4, TH33) on
  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. 25 official manufacturer document quote verified Defective thermistor
  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. 25 official manufacturer document quote verified Check connection of connector (TH4, TH33) on
  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. 25 official manufacturer document quote verified Check resistance value of TH4, TH33 or
  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. 25 official manufacturer document quote verified Replace outdoor controller board.