err-phase-seq on a Danfoss DHP-H: Alarm that indicates that there is an incorrect phase sequence to the compressor. Only display and only the first 10 minutes
Short answer
On a Danfoss heat pump, err-phase-seq means: Alarm that indicates that there is an incorrect phase sequence to the compressor. Only display and only the first 10 minutes. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Alarm that indicates that there is an incorrect phase sequence to the compressor. Only display and only the first 10 minutes.
Part involved: phase sequence (3-phase).
Likely causes:
- Incoming phases in incorrect sequence (3-phase units only). Compressor running backwards may sound loud/rattling and discharge pipe will not get hot.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
What you can check
- Note the message; if it appeared after a power cut, cycle the heat pump's isolator off for a minute or two (user guide advice). If it persists call an electrician/engineer.
What the engineer will check
- Check discharge pipe is hot with compressor running; swap two incoming phases at main terminal block (isolated) and recheck.
Who to ask for: heat pump engineer.
Certification: Qualified electrician / heat pump engineer (electrical fault-finding).
What you might notice
Sources
- Service instructions DHP-A, DHP-A Opti, DHP-AL, DHP-AL Opti, DHP-C, DHP-H, DHP-H Opti, DHP-H Opti Pro, DHP-L, DHP-L Opti, DHP-L Opti Pro (VMGFC302) ↗ · VMGFC302 (© 2010; PDF regenerated 2024-07-10 on assets.danfoss.com) · page printed p.35, p.42 (Table 17); PDF pp.37, 44 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026