B134613 - B134613 Refrigerant Temperature Sensor 1 Open Circuit

Fault Depth Definition

Fault code B134613 represents "Refrigerant Temperature Sensor 1 Circuit Open". This diagnostic identifier belongs to the Body (B-Code) electrical monitoring system within the vehicle's electronic control architecture. In the core logic of the HVAC system, Refrigerant Temperature Sensor 1 plays a critical data acquisition role, and its physical installation location provides real-time feedback on the physical state and operating temperature inside the refrigerant line. This signal is a core input basis for the controller to execute compressor start/stop strategies, expansion valve opening adjustment, and cabin temperature control closed-loop algorithms. When the system determines an "open circuit", it indicates that the analog-to-digital converter inside the Control Unit (Right Domain Controller) has detected an analog voltage signal from the sensor significantly deviating from the preset normal low-level range, identifying it as a circuit open or abnormal voltage rise state.

Common Fault Symptoms

Since the Refrigerant Temperature Sensor is directly linked to the logical judgment and safety protection mechanism of the HVAC system, triggering this fault leads to the following system-level experience anomalies:

• Partial HVAC System Failure: The vehicle's HVAC control strategy will enter a protection mode, which may cause the compressor to stop working or frequently cycle disconnect, unable to maintain the set cabin temperature.
• Reduced Environmental Regulation Capability: Passengers may perceive significantly weakened or lost cooling effects in cooling mode, and defrosting/heating logic is restricted in heating mode.
• System Self-Diagnosis Light Indication: The air conditioning failure indicator light may flash on the dashboard (depending on specific vehicle strategy), or abnormal sensor signals are reported in the vehicle information display system.

Core Fault Cause Analysis

According to the diagnostic logic library of the control unit, triggering this fault code involves anomalies in hardware and physical connection states in three dimensions:

• Hardware Component Failure (Refrigerant Temperature Sensor 1 Failure): The thermistor element inside the sensor has undergone permanent damage or characteristic drift, preventing it from outputting normal voltage divider signals, which are judged as open circuit by the system.
• Line and Connector Faults (Harness or Harness Connector Fault): The physical channel connecting the sensor to the controller appears loose, pin corrosion, open circuit, or shorted to power positive, causing signal voltage to be unable to maintain within a reference range.
• Control Unit Logic Abnormality (Right Domain Controller Failure): There exists interference or input end circuit damage inside the right domain controller responsible for processing this signal input, resulting in logical misjudgment on acquiring effective signals and voltage comparison.

Technical Monitoring & Trigger Logic

The control unit implements dynamic electrical parameter monitoring on the signal chain of Refrigerant Temperature Sensor 1, and the specific determination logic follows the following strict time-window thresholds:

• Detection Target: Output voltage amplitude of the sensor signal loop.
• Numerical Range Threshold: The system has established a clear upper limit warning line for voltage. When it detects the sensor output voltage higher than $4.95\text{V}$, it triggers an open circuit or high-voltage abnormal diagnosis judgment.
• Specific Operating Conditions: Fault monitoring and determination are only effective when "Start switch is in ON gear", and must meet a certain time window of continuous monitoring before the control unit writes this fault code and lights up relevant dashboard indicator lights. This voltage value is usually higher than the theoretical voltage divider upper limit of the sensor in normal operating temperature zones, indicating that the signal line has detached from the expected impedance load.