AU
B2A2C14

DTC B2A2C14 indicates a drive circuit fault in the front passenger side temperature blend door actuator (hot/cold motor), specifically a short to ground (abnormal connection to vehicle ground causing overcurrent) or an open circuit (circuit interruption, infinite resistance) — Seal U

Thermal Management System

DTC B2A2C14 indicates a drive circuit fault in the front passenger side temperature blend door actuator (hot/cold motor), specifically a short to ground (abnormal connection to vehicle ground causing overcurrent) or an open circuit (circuit interruption, infinite resistance).

The integrated Body Control Module (BCM) controls this motor via a PWM signal or stepper drive to adjust the front passenger side hot/cold air mixing ratio, enabling dual-zone climate control.

The BCM sets this DTC upon detecting abnormal motor drive current (excessive or zero), an abnormal position feedback signal, or a LIN communication fault.

This fault prevents front passenger side temperature adjustment (sticking in the cold or hot position).

In severe cases, the BCM may enter protection mode, limiting overall air conditioning system functionality and potentially affecting the thermal management system's control of battery or motor temperatures.

3
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Wiring harness chafing causing short to ground: The wiring harness retaining clip near the evaporator unit detaches, allowing the harness to chafe against the steering column or instrument panel frame. This wears through the power or signal wire insulation, causing a short to ground.
  • 2Internal motor fault: Heating/cooling motor internal coil shorted or burned out, worn carbon brushes causing an open circuit, or gear mechanism binding or slipping causing abnormal drive current.
  • 3Abnormal power supply: Poor contact at dashboard fuse IF03 (especially aftermarket dash cam/GPS power taps causing fuse holder terminal deformation or excessive clearance), resulting in an intermittent power connection or voltage drop.
  • 4Poor connector contact: Backed-out pins, oxidized or corroded pins, or loose terminals in the motor connector behind the glove box cause an intermittent open circuit or high resistance.
  • 5Mechanical binding: Temperature damper shaft corrosion, linkage deformation, or a seized damper blade causes excessive motor load, triggering overcurrent protection and causing the system to falsely detect a short circuit.
What To Do
  • 1
    Connect the VDS or dedicated diagnostic tool, read the complete fault codes, and record the freeze frame data. Attempt to clear the fault codes, adjust the air conditioning temperature, and observe if the fault reoccurs immediately.
  • 2
    Check fuse IF03 (air conditioning system fuse) in the instrument panel power distribution box. Verify the correct rating (usually 10A or 15A). Inspect the fuse holder terminals for spreading or deformation caused by aftermarket equipment. Restore terminal clamping force if necessary.
  • 3
    Remove the front passenger glove box to access the temperature damper actuator (hot/cold motor). Check the wiring harness connector for looseness or backed-out pins. Measure the motor supply voltage (should be 12V ± 0.5V) and check ground wire continuity (resistance should be less than 1Ω).
  • 4
    Disconnect the motor connector and use a multimeter to measure the motor resistance (normal range is usually 30-100 Ω; refer to the workshop manual for exact specifications). A resistance of 0 Ω indicates an internal short circuit. Infinite resistance indicates an internal open circuit.
  • 5
    Inspect the wiring harness routing, focusing on the section from the evaporator housing to the instrument panel crossmember. Check for interference and chafing against the steering column and instrument panel frame. Repair any damaged wiring and re-secure the harness clips.
  • 6
    Manually move the temperature damper linkage and check the damper mechanism for binding, corrosion, or abnormal noise. If necessary, clean and lubricate the damper shaft or replace the evaporator housing assembly.
  • 7
    If the motor and wiring harness are normal, check the drive circuit continuity from the BCM to the motor. Replace the integrated Body Control Module (BCM) if necessary.
  • 8
    After replacing the faulty part, use the diagnostic tool to perform the "Air Flap Position Learning" or "Air Conditioning Initialization" procedure to calibrate the air flap limit positions.
  • 9
    Reinstall all components. Start the vehicle and test the front passenger side temperature adjustment function through its full range (from lowest to highest temperature). Verify the fault code does not return.
Real-World Cases
BYD DTC AI Analysis

Deformed fuse holder pin caused loose connection to passenger side temperature control motor

✓
2018 Qin PRO DM. The customer reported the air conditioning operated only in face-vent mode with no ability to adjust temperature or airflow modes; the passenger side showed no temperature change. VDS read DTCs B2A2A14 (mode motor short to ground), B2A2C14 (passenger temperature control motor short to ground), and B2A2C92 (temperature control motor position not reached). Initial inspection revealed an aftermarket GPS unit tapping power from AC fuse IF03. After removing the added harness and replacing the fuse, the fault remained. Further measurement showed unstable supply voltage to the temperature control motor. Investigation found the fuse holder pins had spread from the use of a wider fuse blade during the GPS installation, causing poor contact. Technicians adjusted the fuse holder pin gap to restore clamping force, eliminating the fault.
Original source ↗
BYD DTC AI Analysis

Wiring harness chafed against steering column causing short to earth.

✓
A 2019 BYD Song MAX came in with an intermittent fault: the passenger-side AC temperature would not adjust while driving, working normally at times and failing completely at others. DTC B2A2C14 stored. The fault appeared intermittently during inspection. Removed the glove box and checked the passenger-side temperature blend motor. The connector had no backed-out pins, but measured abnormal voltage drop on the supply. Traced the wiring and found a retaining clip near the evaporator housing had detached, allowing the harness to chafe against the steering column over time. This wore through the insulation on the passenger-side temperature motor supply wire, causing an intermittent short to ground. Repaired the damaged wiring, re-insulated the harness, and secured the routing to prevent further interference. Fault resolved.
Original source ↗
BYD DTC AI Analysis

Stuck air flap mechanism damaged the motor gear and set a short circuit fault.

✓
A 2017 Qin EV300 developed inoperative passenger-side vent temperature adjustment with the AC on, accompanied by distinct clicking. VDS showed DTCs B2A2C14 and B2A2C92 (temperature blend motor unable to reach position). Removing the passenger-side heater box revealed the temperature blend motor gear mechanism severely worn and seized. Manual actuation of the blend door linkage showed extreme resistance, with corrosion on the door shaft. Mechanical binding of the blend door caused continuous motor stall, excessive current draw triggering the short-to-ground protection (B2A2C14), while gear slippage created the clicking noise. Cleaned and lubricated the blend door linkage, replaced the passenger-side temperature blend motor assembly, and performed blend door position calibration. Temperature regulation returned to normal.
Original source ↗
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.