HVACopediaMidea · Heat pump
PC31 System low pressure protection
What the control is telling you
System low pressure dropped below the limit and the compressor stopped.
Applies to: DLCURAH18-60 AAK/ABK single-zone heat pump outdoor units (18K-60K, regular and High Heat)
Likely causes
- Low refrigerant charge / leak
- Service valve not fully open
- Restriction
- Poor airflow over the evaporating coil (indoor in cooling, outdoor in heating/icing)
Test and repair steps
- Warning: Turn off and lock out power at the outdoor disconnect and wait for the inverter capacitors to discharge before touching the outdoor board or compressor wiring.
- Confirm both service valves are fully open.
- Leak-test and check refrigerant charge.
- Check indoor airflow (cooling) or outdoor coil icing/defrost (heating).
- Check for line set or component restrictions.
Settings for these units
Outdoor unit minimum clearances · Midea DLCURA ducted single-zone inverter heat pump (outdoor)
| Side | Minimum |
|---|---|
| A - top | 24 in. (610 mm) |
| B - right side (service side) | 24 in. (610 mm) |
| C - front (air outlet) | 24 in. (610 mm) |
| D - left side | 4 in. (101 mm) |
| E - rear (air inlet) | 4 in. (101 mm) |
| Above max snow depth | 2 in. (50 mm) |
Side letters taken from Fig. 8 drawing.
Units facing each other: 59 in. (150 cm) or more; do not blow into another unit's inlet.
Models that show this code
12 models in Midea DLCURA ducted single-zone inverter heat pump (outdoor)
Other codes on the same units
- PC10 Outdoor low AC voltage protection
- PC11 Outdoor DC bus high voltage protection
- PC12 DC bus high voltage protection / 341 MCE error
- PC30 System high pressure protection
- PC40 Main chip to compressor-driver chip communication error
- PC42 Compressor start failure
- PC43 Compressor lack-phase protection
- PC44 Outdoor unit zero-speed protection
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Source: Midea/Carrier DLCURA Installation Instructions (Catalog DLCURA-03SI), Table 11 Outdoor Unit Diagnostic Codes, p.19. Summarized in our own words; check the original manual for your model.
Homeowner looking at this code? See what it means for you and when to call a technician.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.