Heat pumps · Error codes · Haier
PBHaier · HPM-Nd2 monobloc (R290, Haier Water Heater Co.)
PB on a Haier HPM-Nd2 monobloc: Loss of synchronism detection (ID number mismatch)
Short answer
On a Haier heat pump, PB means: Loss of synchronism detection (ID number mismatch). The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Loss of synchronism detection (ID number mismatch).
Part involved: compressor, inverter/driver PCB, power supply.
Likely causes:
- Mismatch between main control board and drive board.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
What you can check
- Note the code shown on the controller and the unit model numbers (on the rating plate label) before contacting your installer.
- Check the heat pump's breaker/isolator at the consumer unit is on; do not open any casing.
- If the breaker or RCD trips repeatedly, leave the heat pump switched off and call an engineer; do not keep resetting it.
What the engineer will check
- Follow the manufacturer's troubleshooting flowchart for this code.
- Check supply voltage and phase balance.
- Check compressor windings and inverter/driver PCB per flowchart.
- Check heat-sink cooling and connections.
Who to ask for: Heat pump engineer.
Certification: Heat pump installer competence; F-gas / flammable-refrigerant (R290/R32) handling competence for any refrigerant-circuit work.
What you might notice
Sources
- Installation and service instructions - HPM08/10/12/14/16-Nd2 (Haier R290 monobloc) ↗ · page p.86 (printed; ManualsLib viewer p.92) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026