meaning the physical signal sent by the temperature sensor to the controller has been interrupted, causing the control unit to be unable to acquire real-time thermodynamic parameters of the evaporator surface. From a system principle perspective, this fault occurs between the signal feedback loop and the digital input port, usually manifesting as discontinuity in physical connection or abnormal electrical impedance. As an input variable in a closed-loop temperature control system, the evaporator temperature signal directly participates in compressor logic computation and blend door execution strategy; once this signal link experiences an open circuit, the control unit will determine loss of monitoring capability of the heat exchange state in the evaporating chamber, thus triggering protective logic to maintain system safe operation.

Common Fault Symptoms

When the vehicle detects that DTC B2A2413 fault code is set, drivers may perceive the following air conditioning system function anomalies or instrument feedback during driving:

• Degraded Temperature Control Performance: Air conditioner outlet temperature cannot be effectively adjusted according to the set value, which may cause excessively high or low cabin temperature.
• Restricted System Functionality: The air conditioning compressor may enter a periodic protection mode (e.g., frequent start/stop) or part of refrigeration functions are blocked by software logic.
• Instrument Warning Lights On: "Check Engine", "Service Vehicle" lights appear on the dashboard, or dedicated HVAC system fault indicator lights illuminate.
• Abnormal Data Stream Display: Reading evaporator temperature values in diagnostic tools may show fixed values, random fluctuations, or exceed physical limits (e.g., locked at environmental temperature upper limit).

Core Fault Cause Analysis

Regarding the determination of this fault code, systematic inspection and analysis needs to be conducted from three dimensions: hardware components, wiring connections, and controller logic:

• Hardware Component Anomaly: Evaporator Temperature Sensor Failure itself. This may stem from aging of internal sensing elements, thermistor resistance value drift exceeding specifications, or physical fracture inside the sensor chip causing signal inability to output.
• Wiring/Connector Faults: Harness or Harness Connector Fault. This involves insulation layer damage of wires connecting the sensor, pin corrosion, back-out, poor connection or open circuit situations. If grounding path is open or power line contact resistance is too large, it will also trigger "open" state abnormal voltage reading for the sensor.
• Controller Internal Logic Error: Right Zone Controller Fault. Drift of ADC reference voltage inside control unit, damaged input filter circuit or lost software calibration data may cause normal voltage signals to be misjudged as exceeding safety thresholds, thus erroneously triggering open circuit diagnostics.

Technical Monitoring and Trigger Logic

The generation of this fault code follows strict electrical parameter monitoring logic, specific judgment rules as follows:

• Monitoring Target: Air conditioning system control unit real-time reads analog voltage signals fed back from evaporator temperature sensor to internal A/D converter.
• Fault Condition Setting (Threshold): When diagnostic tool or controller detects sensor output voltage above a specific baseline, it determines open circuit state. Specific numeric threshold is: $> 4.95V$. This voltage value typically corresponds to reference voltage when load is unconnected or line is broken (e.g., pulled high level), indicating signal loop has lost normal divider feedback characteristics.
• Fault Trigger Condition: System only monitors after vehicle power is turned on and in running mode, i.e., after Start Switch is placed in ON position. Under this condition, controller completes self-check procedures and compares sensor real-time readings with calibration range, once voltage confirmed above $4.95V$ exceeds set time window or satisfies continuous detection cycle, fault code will be recorded.

cause excessively high or low cabin temperature.

• Restricted System Functionality: The air conditioning compressor may enter a periodic protection mode (e.g., frequent start/stop) or part of refrigeration functions are blocked by software logic.
• Instrument Warning Lights On: "Check Engine", "Service Vehicle" lights appear on the dashboard, or dedicated HVAC system fault indicator lights illuminate.
• Abnormal Data Stream Display: Reading evaporator temperature values in diagnostic tools may show fixed values, random fluctuations, or exceed physical limits (e.g., locked at environmental temperature upper limit).

Core Fault Cause Analysis

Regarding the determination of this fault code, systematic inspection and analysis needs to be conducted from three dimensions: hardware components, wiring connections, and controller logic:

• Hardware Component Anomaly: Evaporator Temperature Sensor Failure itself. This may stem from aging of internal sensing elements, thermistor resistance value drift exceeding specifications, or physical fracture inside the sensor chip causing signal inability to output.
• Wiring/Connector Faults: Harness or Harness Connector Fault. This involves insulation layer damage of wires connecting the sensor, pin corrosion, back-out, poor connection or open circuit situations. If grounding path is open or power line contact resistance is too large, it will also trigger "open" state abnormal voltage reading for the sensor.
• Controller Internal Logic Error: Right Zone Controller Fault. Drift of ADC reference voltage inside control unit, damaged input filter circuit or lost software calibration data may cause normal voltage signals to be misjudged as exceeding safety thresholds, thus erroneously triggering open circuit diagnostics.

Technical Monitoring and Trigger Logic

The generation of this fault code follows strict electrical parameter monitoring logic, specific judgment rules as follows:

• Monitoring Target: Air conditioning system control unit real-time reads analog voltage signals fed back from evaporator temperature sensor to internal A/D converter.
• Fault Condition Setting (Threshold): When diagnostic tool or controller detects sensor output voltage above a specific baseline, it determines open circuit state. Specific numeric threshold is: $> 4.95V$. This voltage value typically corresponds to reference voltage when load is unconnected or line is broken (e.g., pulled high level), indicating signal loop has lost normal divider feedback characteristics.
• Fault Trigger Condition: System only monitors after vehicle power is turned on and in running mode, i.e., after Start Switch is placed in ON position. Under this condition, controller completes self-check procedures and compares sensor real-time readings with calibration range, once voltage confirmed above $4.95V$ exceeds set time window or satisfies continuous detection cycle, fault code will be recorded.