AU
B2A2B92

This fault code indicates the driver-side HVAC (Heating, Ventilation, and Air Conditioning) temperature blend door actuator (hot/cold blend door motor) cannot reach the target position or the position feedback signal is abnormal — Qin Plus

Thermal Management System

This fault code indicates the driver-side HVAC (Heating, Ventilation, and Air Conditioning) temperature blend door actuator (hot/cold blend door motor) cannot reach the target position or the position feedback signal is abnormal.

The actuator uses a stepper motor or DC motor to drive a gear mechanism, adjusting the hot/cold blend door opening (0-100%).

This accurately controls the airflow mixing ratio through the heater core and evaporator, providing stepless adjustment of the outlet air temperature.

The air conditioning controller (AC ECU) logs this fault code if the deviation between the actual and target positions continuously exceeds the calibrated threshold (typically 5-10%) or if the motor stall current times out.

Triggering conditions include a faulty motor drive circuit, position sensor (potentiometer) signal drift, a binding gear drive mechanism, or excessive mechanical resistance at the blend door shaft.

This fault causes driver-side temperature adjustment failure, abnormal outlet air temperature (stuck excessively cold or hot), unstable temperature control in automatic air conditioning mode, or a clicking gear noise during temperature adjustment.

The B2A2B92 fault code on the Qin Plus indicates the driver-side HVAC temperature blend door actuator cannot reach its target position or has abnormal position feedback. Severity is medium, as it can cause stuck hot or cold air, unstable temperature control, or clicking noises. Common causes include worn actuator gears or a faulty position sensor. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
3
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Worn, broken, or missing teeth in the internal plastic gear set of the air mix door actuator cause drive slippage or binding, preventing the actuator from driving the door to the target position.
  • 2Poor contact, carbon track wear, or resistance drift in the actuator position sensor (potentiometer), causing an inaccurate or erratic position feedback signal.
  • 3Mechanical binding of the air flap linkage or shaft (e.g., foreign objects in the HVAC housing, worn or deformed shaft bushing, lack of lubrication) causes excessive motor load and prevents the motor from reaching its target position.
  • 4Excessive contact resistance in the actuator power supply circuit (oxidized or loose connector pins) or poor ground results in insufficient drive voltage and reduced motor torque.
  • 5Internal drive circuit fault in the air conditioning controller (AC ECU) or loss of software calibration data, causing the ECU to output incorrect control signals or fail to correctly recognize position feedback.
What To Do
  • 1
    Use the BYD VDS or a dedicated diagnostic tool to read fault codes. Confirm B2A2B92 is currently present and cannot be cleared. Check for accompanying fault codes (e.g., B2A2B14 circuit fault, B2A2C12 front passenger side fault). Record the ambient temperature and air flap position data stream at the time the fault occurred.
  • 2
    Perform the air flap actuator self-learning/initialization procedure: Access the air conditioning system special functions using the diagnostic tool and select 'Air Flap Initialization' or 'Actuator Reset', or disconnect the battery negative terminal for 10 minutes and reconnect power. Check if the fault code changes to a history code or clears.
  • 3
    Check the wiring harness connector of the driver's side air mix door actuator (located below the center of the instrument panel, on the driver's side evaporator housing). Inspect the pins for push-out, oxidation, or corrosion. Measure the supply voltage (12V±0.5V) and ground resistance (<1Ω). Check the LIN line or PWM signal line waveform (depending on the specific vehicle topology).
  • 4
    Remove the air flap actuator (accessible from the driver's footwell; dashboard removal is usually unnecessary). Manually rotate the air flap shaft to check for mechanical resistance. Inspect the air flap linkage for detachment or deformation. Inspect the HVAC housing interior for foreign objects (such as leaves or pens) obstructing air flap movement. Clean and apply silicone-based grease if necessary.
  • 5
    Test the actuator assembly: connect the diagnostic tool, perform an active test, and observe if the motor operates smoothly; measure the position sensor resistance (resistance must change smoothly as the motor rotates, without jumps or open circuits, typically 0-5kΩ or 0-10kΩ); measure the motor winding resistance (typically 30-100Ω; refer to the repair manual for specific values).
  • 6
    If the actuator internal gear is damaged or the sensor fails, replace the driver's side air mix door actuator (verify the part number matches the vehicle model; actuators differ between models such as Song MAX and Qin Pro). Before installation, set the air door to the middle position. After installing the actuator, perform the air door position self-learning procedure.
  • 7
    Clear the fault code and perform a functional test: Adjust the temperature through the full range from LO to HI in both automatic and manual modes. Listen for smooth motor operation without abnormal noise. Verify in the data stream that the deviation between the actual position and target position is <3%. Confirm the driver side air outlet temperature changes normally during adjustment.
Real-World Cases
BYD DTC AI Analysis

Yuan PLUS dashboard rattle with DTC B2A2B92

✓
The owner scanned with a Launch golo pro4 and found DTC B2A2B92 (driver-side temperature control motor not reaching position) and B2A2B14 (driver-side temperature control motor short-to-ground or open circuit) in the body module–AC controller. The symptom was a faint, intermittent clicking noise from inside the dashboard, most noticeable when adjusting the temperature or starting the AC. Although the motor wasn't reaching position, cooling and heating still worked. Upon disassembly, the owner found slight wear on the actuator gear. Since the function hadn't completely failed and the part needed ordering, the owner decided to defer the repair and replace the actuator assembly when the fault worsened.
Original source ↗
BYD DTC AI Analysis

Qin EV Intermittent AC Cooling Failure Associated with DTC B2A2B92

✓
The owner reported the vehicle A/C frequently stopped cooling but returned to normal after driving for a period or restarting the vehicle. Scanning showed fault code B2A2B92 (HVAC blend door actuator position fault). Further inspection found the driver's side temperature blend door stuck at maximum heat (100%) when the fault occurred. Even with the temperature set to low, the mixed hot and cold air could not achieve cooling. This case shows B2A2B92 causes not only abnormal noise but can also stick the blend door in a fixed position, causing intermittent A/C failure. Inspect the blend door actuator mechanical linkage and internal gear condition.
Original source ↗
BYD DTC AI Analysis

Song MAX Blend Door Actuator Gear Wear Replacement Case

✓
A 2018 Song MAX owner reported the driver's side AC temperature would not adjust and remained stuck on warm. The technician scanned with VDS and found DTC B2A2B92. Data stream showed target position at 20% with actual position stuck at 95% (full heat). After removing the driver's side temperature blend door actuator, the technician found severe wear and broken teeth on both the drive and driven gears in the internal plastic gear set; the motor spun freely without moving the door. The technician replaced the blend door actuator (part number: HAD-8113210), ran the door initialization procedure, cleared the fault code, and restored normal temperature control. This case represents a typical mechanical failure mode for DTC B2A2B92.
Other Qin Plus 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.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.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Qin Plus →Qin Plus overview →
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.