39 on a Haier heat pump: Low pressure too low (Ps) / compression ratio too high protection
Short answer
On a Haier heat pump, 39 means: Low pressure too low (Ps) / compression ratio too high protection. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 2 sources
What it means
On the Super Aqua Monobloc (R32, AU..FYCRA(HW))
The manual says: Low pressure too low (Ps) / compression ratio too high protection.
Part involved: compressor, pressure switch/sensor, expansion valve, refrigerant charge.
On the Super Aqua Split (R32, AW..SSCHA/SNCHA + HU..WAMNA)
The manual says: Low pressure too low (Ps) / compression ratio too high protection / compression ratio too low protection.
Part involved: compressor, pressure switch/sensor, expansion valve, refrigerant charge.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| 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 manufacturer's troubleshooting flowchart for this code.
- 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
- ATW Service Manual (Super Aqua monobloc) SYJS-03-2019 REV.A ↗ · SYJS-03-2019 REV.A · page p.73 (printed; PDF p.75) · Reviewed 23 September 2026
- Haier HU062WAMNA Service Manual (Super Aqua split R32) ↗ · page p.122 (printed = ManualsLib viewer page) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026