384 on a NIBE heat pump: Com. flt PCA Acc. HTS 2: Communication to accessory card missing; may be due to temporary external disturbance e.g. thunder
Short answer
On a NIBE heat pump, 384 means: Com. flt PCA Acc. HTS 2: Communication to accessory card missing; may be due to temporary external disturbance e.g. thunder. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause.
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What it means
The manual says: Com. flt PCA Acc. HTS 2: Communication to accessory card missing; may be due to temporary external disturbance e.g. thunder.
Part involved: PCB / accessory board communication.
When it shows: Communication to accessory card missing; may be due to temporary external disturbance e.g. thunder.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: no/unknown - Manual reset; cooling supply set to 18 C if HTS controls cooling.
Manual reset: Reset from the controller alarm menu ('reset alarm' / 'Reset alarm and try again'); alarm recurs if the cause remains - NIBE: Manual reset; cooling supply set to 18 C if HTS controls cooling.
What you can check
- Read the alarm text and the 'info/action' help on the controller display (VVM/SMO or S-series smartguide). NIBE's manuals let the homeowner select 'reset alarm' ('Reset alarm and try again' on S-series); if the lamp returns to normal the alarm has cleared. If it comes back, do not keep resetting: select 'aid mode' ('Auxiliary operation' on S-series) if offered, so any electric additional heat keeps heat/hot water going, and contact your installer. Check the breakers for the heat pump, indoor module and any accessories are on at the consumer unit.
What the engineer will check
- Check communication cables and connectors between PCBs/accessory boards, DIP-switch addressing, power supply to the accessory board, and that accessories activated in the menu are actually fitted.
Who to ask for: NIBE-trained heat pump installer (NIBE PRO / VIP).
Certification: Electrical work to BS 7671 by a competent person.
What you might notice
Sources
A code explains what the controller detected, not a confirmed root cause.