H06.99 on a Baxi HP60 / Baxi Assure HP55 High Temperature Monobloc ASHP: Compressor alarm Alarm related to the compressor raised by the inverter
Short answer
On a Baxi heat pump, H06.99 means: Compressor alarm Alarm related to the compressor raised by the inverter. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Compressor alarm Alarm related to the compressor raised by the inverter.
Part involved: refrigerant pressure / temperature.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: yes - system restarts automatically when the cause disappears (may run in degraded/back-up mode meanwhile).
Manual reset: not required once cause removed.
What you can check
- Note the exact code shown on the controller and when it appeared.
- Check the outdoor unit is not blocked by leaves, debris, snow or covers and has clear airflow.
- The manual's user steps allow switching the system off and on once to see if the error clears; if the code returns, contact the installer.
- If the code persists or returns, contact a heat pump engineer.
What the engineer will check
- Diagnose per manufacturer service procedure (manual gives description only).
Who to ask for: heat pump / refrigeration engineer (F-gas).
Certification: F-gas certification (Category I) for refrigerant work; competence with flammable A3 refrigerant R290.
What you might notice
Sources
- Installation, user and service manual - Indoor unit ASHP Control ↗ · 7887625 - v04 - 22072025 · page 133 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026