Mitsubishi Electric · Heat pumps · Mitsubishi Electric Ecodan PUZ-WM outdoor unit (R32)
EbMiswiring of indoor/outdoor unit connecting wire (reverse wiring or disconnection)
Name in the manufacturer's documentation (service manual): Miswiring of indoor/outdoor unit connecting wire (reverse wiring or disconnection)
[1]
In plain words (editorial)
Miswiring of the indoor/outdoor connecting wire (reverse wiring or disconnection) – the indoor unit number could not be set within 4 minutes after power on. The service manual checks the indoor/outdoor connecting wire (disconnection, looseness, polarity, diameter and length), overlapping refrigerant addresses and noise on the transmission path; one step is to turn the power off once and on again.
When to call a service technician: Contact your installer or a Mitsubishi Electric service technician.
✎ editorial – written from the cited sources, not a manufacturer statement. Status: draft.
For technicians
Detection conditions (source text)
- Abnormal if the indoor unit number cannot be set within 4 minutes after power on because of miswiring[2]
Possible causes (source text)
- Contact failure or miswiring of indoor/outdoor unit connecting wire[3]
- Diameter or length of indoor/outdoor unit connecting wire is out of specified capacity[4]
- Defective transmitting receiving circuit of outdoor controller circuit board[5]
- Defective indoor power board[6]
- Do NOT use refrigerant address 0, as 0 is used for FTC (Master)[7]
- Noise has entered into power supply or indoor/outdoor unit connecting wire[8]
Steps given by the manufacturer (source text)
- Check disconnection or looseness or polarity of indoor/outdoor unit connecting wire[9]
- Check diameter and length of indoor/outdoor unit connecting wire. Total wiring length: 80 m[10]
- Turn the power off once, and on again to check[11]
- Check if refrigerant addresses (SW1-3 to SW1-6 on outdoor controller circuit board) are overlapping[12]
- Check transmission path, and remove the cause[13]
⚠ Work on refrigerant circuits, mains electricity and PV DC wiring is for qualified technicians only.
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] 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. 24 official manufacturer document quote verified
- [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. 24 official manufacturer document quote verified
abnormal if the indoor unit number cannot
- [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. 24 official manufacturer document quote verified
contact failure or miswiring of
- [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. 24 official manufacturer document quote verified
diameter or length of indoor/
- [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. 24 official manufacturer document quote verified
defective transmitting receiving
- [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. 24 official manufacturer document quote verified
defective indoor power board
- [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. 24 official manufacturer document quote verified
do not use refrigerant
- [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. 24 official manufacturer document quote verified
noise has entered into power
- [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. 24 official manufacturer document quote verified
check disconnection or looseness or polarity
- [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. 24 official manufacturer document quote verified
total wiring length: 80 m
- [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. 24 official manufacturer document quote verified
turn the power off once, and on again to
- [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. 24 official manufacturer document quote verified
check if refrigerant addresses (sw1-3 to
- [13] 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. 24 official manufacturer document quote verified
check transmission path, and remove the