AU
B2A2A14

DTC B2A2A14 indicates a short to ground or open circuit in the A/C system mode door actuator (Mode Motor) control circuit — Atto 8

Thermal Management System

DTC B2A2A14 indicates a short to ground or open circuit in the A/C system mode door actuator (Mode Motor) control circuit.

The mode motor is the core actuator in the HVAC door system, switching the door between FACE, FOOT, DEF, and other positions.

This fault indicates the integrated Body Control Module (BCM) detects abnormal circuit current (high current indicates a short circuit; low current indicates an open circuit) or a lost position feedback signal when driving the mode motor.

Consequently, the BCM cannot accurately control the door position.

This fault locks the A/C outlet mode in a fixed position or causes complete failure, severely impacting driving comfort and safety (especially if the front windshield defogging function fails).

This fault usually appears alongside DTC B2A2A92 (mode motor fails to reach position).

As a hard-wired circuit fault, it requires immediate repair to prevent further damage to the BCM drive circuit.

5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Mode motor internal damage: Worn motor brushes or burnt coils cause an internal short or open circuit, resulting in abnormal resistance (normal: 30-50 Ω).
  • 2Wiring harness connector fault: The mode motor 6-pin connector (especially pin 6 ground and pins 1-2 drive) exhibits backed-out terminals, corrosion, looseness, or poor contact; or vibration wear causes an open or short circuit in the wiring harness near the evaporator case.
  • 3Poor fuse holder contact: Drawing power for aftermarket devices (dash cam, GPS) deforms or creates excessive clearance at the instrument panel power distribution box IF03 (A/C fuse) or IF23 fuse holder terminals, causing intermittent power supply interruption.
  • 4Integrated Body Control Module (BCM) fault: Damaged BCM internal mode motor drive circuit (H-bridge driver chip) prevents normal forward and reverse drive voltage output.
  • 5Air flap mechanism mechanically jammed: The air flap linkage inside the evaporator unit seizes, deforms, or a foreign object blocks it, overloading and burning out the motor, triggering short-circuit protection.
What To Do
  • 1
    Diagnostic scan: Connect the VDS diagnostic tool, read the integrated body controller fault codes, confirm B2A2A14 is present, and check for related fault codes such as B2A2A92 and B2A2C14. Read the data stream to verify the mode motor position feedback value changes with operation.
  • 2
    Power supply and fuse check: Check dashboard distribution box IF03 (air conditioning system fuse) and IF23. Verify correct fuse ratings (typically 10A or 15A). Inspect the fuse holder terminals for deformation or excessive clearance caused by tapping power for external equipment. Repair the terminal clearance if necessary.
  • 3
    Motor body inspection: Remove the mode motor (located inside the instrument panel, right of the evaporator housing). Check the connector for looseness, backed-out pins, or water corrosion. Measure the motor resistance between pins 1 and 2. The normal value is approximately 30-50 Ω. 0 Ω indicates a short circuit; infinite resistance indicates an open circuit. Manually rotate the motor output shaft; it must turn smoothly without binding.
  • 4
    Harness continuity test: Disconnect the BCM and mode motor connectors. Measure continuity between motor connector pin 6 (ground) and body ground, and between pins 1-2 (drive) and the corresponding BCM pins. Resistance must be less than 1 Ω. Measure the insulation resistance of each pin to ground. Resistance must be greater than 10 MΩ.
  • 5
    Air flap mechanism inspection: Manually turn the evaporator housing air flap linkage to check for binding, abnormal noise, or incomplete travel; check if the connection between the air flap linkage and the motor is detached.
  • 6
    Control module verification: After verifying the wiring is normal, connect an external 12V power supply directly to the mode motor to test forward and reverse rotation. If the motor operates normally but the BCM still reports a fault, replace or repair the integrated body control module.
  • 7
    Repair and verification: Replace the faulty mode motor or repair the wiring harness, and resolve poor contact at the fuse holder; clear the fault code, operate the air conditioning control panel to test switching between all modes, and confirm fault resolution and no abnormal noise.
Real-World Cases
BYD DTC AI Analysis

BYD air conditioning mode unadjustable – Poor contact at fuse holder

✓
Symptoms: Customer reported the air conditioning only worked in dashboard vent mode with no ability to adjust airflow direction or temperature. Internal/external recirculation and mirror defrost were also inoperative. Diagnosis: VDS scan showed DTCs B2A2A14 (mode motor short to ground or open circuit), B2A2A92 (mode motor position not reached), and B2A2C14 (passenger side temperature motor short to ground or open circuit) stored in the Integrated Body Controller; the codes would not clear. Inspection found an aftermarket GPS and dash cam tapped into air conditioning fuse IF03. Removed the add-on harness and replaced the fuse with an OEM unit, but the fault persisted. Pin 6 at the mode motor and temperature motor connectors showed no continuity to ground. Further inspection revealed the GPS fuse blade was wider and thicker than the original. Repeated insertion and removal had spread the terminals in the IF03 fuse holder, causing poor contact. Resolution: Resized the fuse holder terminals and reinstalled an OEM fuse. Fault completely resolved.
Original source ↗
BYD DTC AI Analysis

BYD Yuan Plus/ATTO 3 drive motor short circuit fault

✓
**Symptoms:** HVAC mode door inoperative. Vent mode won't switch (e.g., cannot change from face-level to footwell or defrost) or remains stuck in one position. **Diagnosis:** Per the BYD Yuan PLUS/ATTO 3 (SC2E) repair manual, DTC B2A2A14 is defined as 'Mode Motor Shorted to Ground or Open-circuited'. Check: 1. Mode motor harness connector K.J for loose connections, backed-out pins, or corrosion; 2. Mode motor resistance for opens or shorts; 3. Continuity of control lines (motor drive and position feedback) between the Integrated Body Control Module (BCM) and mode motor; 4. Motor position feedback signal voltage. **Fix:** Replace the mode motor assembly if the motor has an internal short or open. Repair the harness for any opens or shorts.
Original source ↗
BYD DTC AI Analysis

BYD EV: Multiple air conditioning motors failed simultaneously

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Symptoms: Vehicle AC developed multiple simultaneous function failures. Airflow mode adjustment, hot/cold switching, and intake/recirculation switching were all inoperative; the system could only maintain a single operating mode. Diagnosis: Connected VDS and retrieved codes from the integrated body control module: B2A2A14 (mode actuator short to ground or open), B2A2A92 (mode actuator position not reached), B2A2B14 (temperature actuator short to ground or open), and B2A4B14 (recirculation actuator short to ground or open). Inspected shared power and ground circuits, checking instrument panel fuse box fuses IF03 (AC fuse) and IF23 (mirror defrost fuse). Measured actuator connector pin definitions: pins 1-2 for motor drive, pins 4-5 for position feedback, and pin 6 for ground. Found open circuit in the wiring between pin 6 of the mode and temperature actuator connectors and the body control module. Solution: Inspected the fuse holder and found terminals deformed with excessive clearance due to aftermarket accessories (dash cam, GPS) tapping power. Repaired the fuse holder terminals to ensure proper contact. Cleared fault codes and retested all AC mode functions.
Original source ↗
BYD DTC AI Analysis

BYD air conditioning mode motor position sticking with abnormal noise

✓
Symptoms: Clicking or knocking noise from the air conditioning when adjusting mode settings, or the mode fails to switch fully. Sometimes air only blows to face level and not to the feet, or defrost mode won't activate. Diagnosis: VDS scan shows fault code B2A2A14 (mode motor short to ground or open circuit) accompanied by B2A2A92 (mode motor position not reached). Remove the mode motor and manually rotate the damper linkage to check for binding. Measure mode motor resistance to check for internal damage. Inspect the connector between the evaporator housing and steering column for bent or backed-out pins. Inspect the connector where the AC wiring harness joins the instrument panel harness. Solution: If the damper linkage binds, clean and lubricate the damper mechanism or replace the evaporator housing assembly. If the mode motor is internally damaged (abnormal resistance, short or open circuit), replace the mode motor. If the wiring harness connector has backed-out pins or poor contact, repair or replace the harness. Some vehicle models also require updating the integrated body controller software version.
Original source ↗
BYD DTC AI Analysis

BYD Qin/Song series climate control air door actuator fault

✓
Symptoms: After some time in service, the AC vent mode suddenly failed to adjust or did not respond to mode changes. The instrument cluster may show no warning light, but AC function is limited. Diagnosis: Scanned for DTCs and found B2A2A14. Located the mode motor (usually inside the dashboard near the evaporator) and checked the connector for looseness. Measured motor supply voltage (should be 12V) and ground. Compared the data stream with a known-good vehicle and verified the mode motor position feedback matched actual position. Solution: Replaced the faulty mode door actuator (mode motor). Inspected and repaired the wiring harness, focusing on poor contact at the fuse holder. Performed AC system self-learning or mode motor position calibration (required on some models).
Original source ↗
Other Atto 8 Fault Codes
B1108For 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.B1109DTC B1109 indicates an open circuit in the communication line between the air conditioning system PM2.5 air quality sensor (dust concentration sensor) and the air conditioning control unit (AC ECU), or an open circuit within the sensor internal circuitry. Typically located in the air conditioning intake duct, this sensor monitors real-time PM2.5 particle concentration inside and outside the vehicle. It provides data to the automatic air conditioning system for intelligent switching between fresh air and recirculation modes and for controlling the air purification device. During an open circuit fault, the AC ECU cannot receive the air quality signal, triggering the system fail-safe mode. Symptoms typically include failure of the automatic recirculation function, abnormal air purification indicator light operation, or abnormal air quality data displayed on the air conditioning panel. Severe cases may compromise the cabin environment control strategy, but do not directly affect vehicle driving safety.B110913DTC B110913 indicates an open signal circuit for the PM2.5 rapid detector (in-cabin air quality sensor). This sensor typically mounts inside the air conditioning system intake duct. It monitors in-cabin PM2.5 concentration in real time and provides data to the automatic air conditioning system for intelligent control of the air purification function. The BYD diagnostic protocol uses sub-code '13' to specifically indicate an open signal circuit. Although this fault theoretically affects a comfort feature, BYD Qin series vehicles classify it as a Level 3 (severe) fault. This classification occurs because the air conditioning system interacts with the battery thermal management system (e.g., monitoring battery cooling intake air quality). The fault can disable the automatic air conditioning mode and prevent the air purification function from operating. In extreme cases, it affects the battery compartment intake air quality assessment, triggering the 'repair immediately' strategy.B110AThis DTC indicates interrupted CAN bus communication or abnormal data between the air conditioning control unit (ACU) and the PM2.5 air quality sensor. The PM2.5 sensor monitors particulate concentration inside and outside the vehicle and provides the basis for purification control in the automatic air conditioning system. The ACU triggers this fault if it fails to receive a valid CAN message from the sensor within the specified period (usually 100-500 ms), if message verification fails, or if the signal frame times out. Although this fault does not affect vehicle driving safety, it disables the automatic air purification function. The air conditioning system cannot automatically switch between recirculation and fresh air modes or activate the air purification mode based on air quality. A persistent fault may restrict the thermal management strategy.
Data confidence: Official This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.