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B2AB64B

DTC B2AB64B indicates the electric A/C compressor internal temperature monitoring point detects an abnormally high temperature or an abnormal temperature signal — Atto 3

Thermal Management System

DTC B2AB64B indicates the electric A/C compressor internal temperature monitoring point detects an abnormally high temperature or an abnormal temperature signal.

On 2019 BYD Qin EV models, this fault typically indicates the electric scroll compressor (BYD in-house or third-party supplied) internal motor winding temperature, power module (IPM) temperature, or compressor housing temperature exceeds the normal operating range (typical threshold: 110–130°C).

When this fault occurs, the compressor controller enters protection mode.

It limits compressor speed or stops operation to prevent insulation damage or mechanical seizure.

Because the Qin EV uses the A/C system for battery thermal management (the battery chiller integrates into the A/C circuit), this fault causes loss of cabin cooling and can reduce traction battery cooling capacity, subsequently triggering battery thermal management power derating protection.

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Cases Logged
Real-World Cases
BYD DTC AI Analysis

Minor refrigerant leak triggered compressor thermal protection.

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2019 Qin EV, 80,000 km. After 30 minutes of summer highway driving, the air conditioning suddenly stopped cooling. No warning lights on the dash, but DTC B2AB64B logged. Freeze frame showed compressor internal temperature at 128°C (threshold 125°C) and high-side pressure at 2.8 MPa (elevated). Inspection found oil residue at the lower left corner of the condenser; a pressure test revealed a minor leak. Recovered only 450g of refrigerant (standard 650g). Replaced the condenser and seals, recharged the refrigerant, and ran continuous high-speed testing for 2 hours. Compressor internal temperature stabilized at 85-95°C. Fault resolved.
BYD DTC AI Analysis

Loose connection in compressor temperature sensor wiring harness causing false alarms

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Vehicle intermittently logged DTC B2AB64B approximately once per week, clearing after restart. Diagnostic tool showed internal temperature of -40°C when fault occurred (sensor open-circuit value). Checked compressor controller connector B12: pin 3 (temperature signal) had loose retention and detached when lightly pulled. Repaired pin, applied conductive grease, and re-secured harness routing to prevent vibration interference. No recurrence after 3 months.
BYD DTC AI Analysis

Seized compressor bearing caused high temperature

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At 60,000 km, the vehicle emitted a sharp screech after turning on the air conditioning, then set DTC B2AB64B and shut down the AC. Tore down the compressor: the scroll bearing was grinding dry from oil starvation; increased rotor axial clearance caused rotor-to-stator rubbing, overheating and discoloring the windings locally. Three-phase winding resistance measured 1.2Ω/1.3Ω/0.8Ω (imbalanced) with insulation resistance down to only 2MΩ. Replaced the electric compressor assembly, flushed the AC lines—found substantial metal debris—and replaced the receiver drier and expansion valve. Fault cleared completely.
BYD DTC AI Analysis

High ambient temperature and high battery cooling load caused overheating

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40°C summer ambient. During fast charging with battery cooling active, the compressor ran continuously at 6000rpm and set DTC B2AB64B. Insufficient condenser cooling combined with high ambient temperature caused the fault. The cooling fan ran at high speed, but condenser fins were severely clogged with catkins. After deep-cleaning the condenser, compressor internal temperature dropped from 122°C to 105°C under identical conditions; protection did not trigger again. Advised owner to clean the condenser regularly, particularly during pollen and catkin season.
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For the BYD Song MAX (2017–2019), DTC B1108 indicates a short circuit in the PM2.5 air quality detection module (dust sensor) or its wiring harness. The sensor uses laser scattering to detect in-cabin and outside PM2.5 concentrations and transmits data to the HVAC ECU via the LIN bus or an analog signal. Short circuit conditions include: 1) Sensor power supply wire (+5V/+12V) shorted to ground 2) Signal wire shorted to power or ground 3) Short circuit in the sensor's internal photoelectric detection circuit This fault prevents the automatic climate control from switching between fresh air and recirculation based on air quality. The system enters fail-safe mode (typically forced recirculation). Severe short-circuit current can destroy the HVAC ECU sampling circuit. The system classifies this as a Level 3 severe fault and restricts vehicle operation to prevent electrical fires or controller damage. For other BYD models (such as the Qin EV, E5, and Song DM), B1108 indicates a driver-side sunload sensor fault, reflecting differences in DTC definitions across models.B110811This DTC indicates a short circuit in the air conditioning system PM2.5 air quality sensor (rapid detector). Specifically, abnormal continuity exists between the sensor power supply circuit or signal output circuit and body ground or battery positive. This causes the control module (ACU/air conditioning controller) to detect abnormal current or a voltage signal outside the valid range (typically 0V or supply voltage). The PM2.5 sensor monitors internal and external particulate concentrations, providing the data the automatic air conditioning system uses to switch between fresh air and recirculation modes. A short circuit disables the air quality monitoring function. This fault may force the air conditioning system into recirculation protection mode and trigger related thermal management system faults, as the air conditioning system acts as a key actuator in vehicle thermal management. In severe cases, the short circuit current can damage the internal sampling circuit of the air conditioning controller or overheat the wiring harness.
Data confidence: Community This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.