BYD ATTO 3 (e-Platform 3.0) B2AB149 Air Conditioner Compressor Motor Phase Loss Fault

B2AB149 indicates a phase loss has been detected in the electric A/C compressor motor. The fault affects the compressor’s three-phase electric motor drive, which converts high-voltage electrical power into mechanical compressor operation for refrigerant circulation and cabin cooling. The BYD ATTO 3 uses BYD’s e-Platform 3.0 architecture, with this generation introduced from 2022 and continuing onward.

Symptoms

• Air conditioner does not produce cold air
• Compressor fails to start
• A/C cooling may be intermittent
• Compressor may stop shortly after activation
• Climate control warning may be displayed
• Cabin temperature remains higher than requested
• Compressor-related fault codes may be stored
• High-voltage HVAC system may disable compressor operation

Possible Causes

• Internal A/C compressor motor phase fault
• Open circuit in a compressor motor phase
• Damaged high-voltage compressor wiring
• Loose or damaged compressor connector
• Poor electrical terminal contact
• Internal compressor inverter or motor-drive fault
• High-voltage power supply problem
• Compressor winding fault
• Insulation or electrical integrity fault
• Low or unstable vehicle electrical supply
• Compressor control-module fault
• Thermal-management or protection-system intervention

Diagnosis

Diagnosis should begin by confirming B2AB149 and checking for related compressor, high-voltage, insulation, power supply, and communication faults. Compressor operating status, high-voltage supply, phase-related electrical data, wiring and connector condition, and compressor control information should then be evaluated against manufacturer specifications.

The diagnostic direction should distinguish between an external wiring or power-supply fault and an internal compressor motor or inverter fault before compressor replacement is considered. Because this system operates at high voltage, manufacturer isolation procedures and appropriate EV safety equipment are essential during testing. For New Zealand owners, confirming the electrical cause before replacing the high-voltage compressor can help avoid unnecessary repair costs.

Accurately diagnosing this fault often requires manufacturer testing procedures, wiring diagrams, connector pinouts, specifications, and system calibration information. Access to the factory service manual significantly reduces diagnostic time and helps prevent unnecessary parts replacement.

Applicable Years

2022, 2023, 2024, 2025, 2026, onwards

To order the correct OEM Service and Repair Manual for your BYD ATTO 3, submit your request using the form below and our team will provide the ordering details.