AU
B2A2C92

This DTC indicates the front passenger side temperature flap actuator (air mix flap motor) cannot reach the target position or the position feedback signal is abnormal — Seal U

Thermal Management System

This DTC indicates the front passenger side temperature flap actuator (air mix flap motor) cannot reach the target position or the position feedback signal is abnormal.

The integrated Body Control Module (BCM) drives this stepper/DC motor via the LIN bus or PWM signal to adjust the air mix flap opening and control the front passenger outlet temperature. "Cannot reach position" means the motor fails to reach the target angle within the set time (typically 3-5 seconds), or the position sensor feedback voltage deviates from the expected value by more than the threshold (generally >5%).

This fault disables front passenger temperature adjustment (no hot or cold air).

Severe cases may cause abnormal flap noise or trigger air conditioning system protection mode, but typically do not affect vehicle driving safety.

3
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Internal damage to the temperature damper actuator motor (gear set wear, motor rotor binding, or excessive carbon brush wear), resulting in insufficient driving force to overcome damper resistance.
  • 2Poor wiring contact or open circuit, especially excessive pin clearance or deformation at the A/C fuse socket (e.g., IF03) in the instrument panel power distribution box, causing excessive power supply voltage drop (common after tapping power for aftermarket accessories such as GPS or dash cams).
  • 3Air flap mechanism jammed (broken air flap shaft, deformed plastic flap, detached foam seal causing binding, or foreign object blocking the air duct), triggering motor stall protection.
  • 4Integrated Body Control Module (BCM) internal driver chip fault or abnormal LIN bus communication, causing loss of motor drive signal or position sampling circuit fault.
  • 5Temperature flap position sensor (potentiometer) signal drift or open circuit; abnormal feedback voltage causes the BCM to incorrectly determine the flap is not in position.
What To Do
  • 1
    Connect the VDS diagnostic tool, read all fault codes, and record the freeze frame data. Check for related fault codes accompanying B2A2C92, such as B2A2C14 (short to ground/open circuit). Check if the BCM software version requires an update.
  • 2
    Check the A/C system fuse (IF03, etc.) in the instrument panel power distribution box. Focus on inspecting the fuse holder terminals for excessive clearance, looseness, or burn damage from aftermarket equipment (GPS, dash cam) power taps. Measure the voltage drop across the fuse; it must be <0.1 V.
  • 3
    Remove the front passenger side glove box or lower dashboard trim panel. Visually inspect the air mix door actuator (usually located on the right side of the HVAC assembly) for damage, and check the connector for oxidation or backed-out terminals. Measure the motor power supply (constant 12V), ground (<0.5Ω), and continuity of the LIN line/PWM signal line.
  • 4
    Disconnect the motor connector and use an oscilloscope or multimeter to measure the BCM control signal output. If the signal is normal, apply an external 12V power supply directly to the motor to verify full travel operation. Listen for abnormal gear slipping noises. Measure the position sensor feedback voltage; it must change linearly with rotation (0.5-4.5V).
  • 5
    Remove the actuator and manually move the air flap shaft to check the internal HVAC mechanism for binding or looseness. Check if the air flap sealing strip has detached and is obstructing movement. If necessary, use a borescope to check for foreign objects inside the air duct.
  • 6
    If the actuator is faulty, replace it with a genuine temperature air flap actuator (align to the zero position during installation; some models require a diagnostic tool for air flap position learning/calibration). Clear the fault code, then test the adjustment function across all positions from full cold to full hot.
Real-World Cases
BYD DTC AI Analysis

Excessive clearance in fuse holder pins caused multiple motors to fail

✓
A 2018 Qin PRO DM owner reported the AC temperature and mode could not be adjusted. VDS scanning revealed motor DTCs B2A2C92 (passenger side temperature control motor position not reachable) and B2A2A92 (mode motor position not reachable). Inspection found a GPS retrofit tapping power from the air conditioning fuse. The GPS fuse blade was wider than OEM spec, spreading the IF03 fuse holder terminals and increasing contact resistance. Although the fuse appeared intact, insufficient voltage caused multiple air door actuators to fault simultaneously. Repaired the fuse holder terminals, restored the factory fuse, removed the added wiring harness, and cleared the fault.
Original source ↗
BYD DTC AI Analysis

Temperature blend door actuator internal gears slipping

✓
A 2019 Song MAX had constant cold air from the passenger side AC; the temperature could not be adjusted. The scan tool retrieved DTC B2A2C92. Live data showed target position at 100% (full heat) while actual position remained at 0% (full cold). Measured the actuator power supply, ground, and signal lines — all normal. Applied external power: the motor ran but the damper shaft did not turn, indicating worn plastic gears slipping inside the actuator. Replaced the passenger side temperature damper actuator. The actuator now follows temperature adjustment commands normally, the DTC cleared, and temperature adjustment function restored.
Original source ↗
BYD DTC AI Analysis

HVAC damper shaft binding, causing motor stall

✓
A 2017 Qin EV300 developed a clicking noise after the AC turned on, followed by passenger-side temperature control failure and DTC B2A2C92. Technicians removed the HVAC assembly and found the blend door shaft seized at the bushings from dust accumulation—the blend door had remained stationary for an extended period because the vehicle was always driven in recirculation mode with the temperature set to low. The actuator motor tried to drive the shaft but stalled against the resistance, eventually overheating and storing the fault. They cleaned the shaft bushings, applied specialized silicone-based grease, manually verified smooth operation, and reinstalled the original actuator (motor undamaged). Fault resolved. Advise the owner to regularly switch between temperature modes to prevent blend door mechanism seizure.
Other Seal U 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.