Carrier heat_pump Error Code 31

What does 31 mean?

Compressor discharge temperature is critically high. Compressor is at risk of damage.

Common causes

• Low refrigerant
• Compressor valve failure
• Liquid slug in compressor
• High ambient temperature operation

Diagnostic & testing steps

1. 1. Check discharge temperature: should be below 225°F
2. 2. Check suction superheat: normal is 10-20°F
3. 3. Check subcooling: normal is 10-15°F
4. 4. Listen for abnormal compressor sounds
5. 5. Measure compressor amp draw vs nameplate RLA

Tools required

• Manifold gauge set
• Temperature clamp probe
• Amp clamp

OEM parts & part numbers

Compressor, Refrigerant (R-410A)

Part numbers: 5F40NCA036000

Safety warning

⚠️ COMPRESSOR HAZARD: High discharge temps can cause catastrophic compressor failure. Shut down immediately if overheating.