Heat pumps · Error codes · Carrier
31Carrier · AquaSnap / AquaSnap Plus 30AWH (R410A inverter monobloc, 2010-2018 generations)
31 on a Carrier AquaSnap / AquaSnap Plus 30AWH: High pressure system error
Short answer
On a Carrier heat pump, 31 means: High pressure system error. 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: High pressure system error.
Likely causes:
- Refrigerant pressure/temperature outside limits (charge, restriction, airflow, 4-way valve).
Is it safe?
Switch the heat pump off at its isolator and call an engineer.
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
What you can check
- Note the code/LED pattern and the model from the rating plate, then contact a heat pump/refrigeration engineer.
- Check the heat pump's breaker/isolator at the consumer unit is on.
- Check the outdoor unit is not blocked by leaves, snow or debris.
What the engineer will check
- Check refrigerant pressures/charge, coil condition, 4-way valve, pressure switches.
Who to ask for: refrigeration / heat pump engineer.
Certification: F-gas certification (refrigerant circuit work) and electrical competence.
What you might notice
Sources
- Carrier 30AW AquaSnap Plus Reversible Inverter - Installation, Operation and Maintenance Instructions (air/water cycle heat pump), Order No. L010130H42 01.2017 (supersedes 12.2015) ↗ · L010130H42 01.2017 · page 26 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026