47 on a Hisense Hi-Therma Monobloc: Activation of Low Pressure Decrease Protection Device (Vacuum Operation Protection)
Short answer
On a Hisense heat pump, 47 means: Activation of Low Pressure Decrease Protection Device (Vacuum Operation Protection). 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: Activation of Low Pressure Decrease Protection Device (Vacuum Operation Protection).
Part involved: high-pressure switch PSH, expansion valve, refrigerant charge, compressor.
Likely causes:
- Insufficient Refrigerant.
- Refrigerant Piping.
- Clogging.
- Expansion Valve Locking at Close Position (Loose Connector).
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| 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.
- Check the outdoor unit is not blocked by leaves, debris, snow or ice and that nothing is stored against the grilles.
What the engineer will check
- Follow the handbook alarm-code flowchart (O.U. section from printed p.335, I.U. section from viewer p.383).
- Check refrigerant pressures and charge (F-gas / flammable refrigerant competent person only).
- Check expansion valve, pressure switches/sensors and discharge temperature.
- Check outdoor coil airflow and blockages.
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
- Air-to-Water Heat Pump Technical, Installation and Service Handbook - Hi-Therma Series (TCY12021017E) ↗ · TCY12021017E · page p.333 (printed; ManualsLib viewer p.354) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026