Application of Automotive HVAC Temperature-Pressure Integrated Sensors in Refrigerant Pressure and Temperature Monitoring

In modern vehicles, the air conditioning system is no longer just a comfort feature; it is a core subsystem affecting efficiency, safety, and driving experience. Refrigerant circulates between the compressor, condenser, expansion valve, and evaporator, and its precise pressure and temperature changes directly determine cooling/heating performance, energy consumption, and system lifespan. Reliable monitoring of these critical parameters in limited space is a common challenge for OEMs and component suppliers.

The automotive HVAC temperature-pressure integrated sensor addresses this challenge by combining pressure and temperature measurement in a single unit. Installed at key points in the AC pipeline, it outputs real-time refrigerant pressure and temperature simultaneously. This integration reduces the number of sensors, pipeline connections, and wiring complexity, lowering potential leakage risks while aligning with vehicle trends of lightweight design, modularity, and high reliability. Nexisense’s integrated temperature-pressure sensors are increasingly recognized in both traditional fuel and new energy vehicles for their stability and engineering adaptability.

Core Monitoring Requirements in Automotive HVAC Systems

Automotive air conditioning operates as a closed refrigeration cycle, with refrigerants (e.g., R134a, R1234yf, or CO₂) undergoing compression, condensation, expansion, and evaporation. Each stage requires precise pressure and temperature ranges:

• Compressor outlet: high-pressure, high-temperature zone (typical 1.5–3.0MPa, 80–120℃)

• Condenser outlet: high-pressure, medium-temperature zone

• Evaporator inlet: low-pressure, low-temperature zone

• Overall system: must prevent overpressure, underpressure, freezing, or overheating

Traditional solutions use separate pressure switches/sensors and temperature sensors, which involve multiple installation points, complex interfaces, and higher leakage risks, occupying valuable engine bay space. As new energy vehicles proliferate, heat pump HVAC systems require higher monitoring precision and faster response, making integrated temperature-pressure sensors a superior choice.

Technical Highlights of Nexisense Integrated Temperature-Pressure Sensors

Nexisense automotive HVAC temperature-pressure integrated sensors use high-precision pressure-sensitive elements combined with NTC temperature elements for synchronized measurement. Key features include:

• Wide measurement range: 0–5MPa for pressure (suitable for high/low side), -40℃ to +150℃ for temperature

• High accuracy and stability: ±1.0%FS for pressure, ±1℃ for temperature, minimal long-term drift

• Fast response:<5ms for pressure, <10s for temperature

• Durability: vibration resistance 10–2000Hz, shock resistance, corrosion resistance (compatible with various refrigerants)

• Flexible output: analog voltage, PWM, LIN, or CAN for seamless ECU integration

The integrated probe design combines the pressure diaphragm and temperature element to reduce thermal inertia error, ensuring measured temperature closely reflects the actual refrigerant value. The sensor housing uses engineering plastic with metal interface, lightweight and compact, with IP67 protection for high temperature, humidity, and oil exposure in the engine bay.

Practical Advantages in Automotive AC Pipelines

1. Improved Cooling/Heating Efficiency and Energy Performance: Real-time refrigerant pressure-temperature correlation allows the ECU to dynamically adjust compressor speed (especially electric compressors), expansion valve opening, and fan speed, avoiding wasted energy. In EV heat pump systems, this significantly improves winter heating COP.

2. Enhanced System Safety: On detection of abnormal high pressure (>3.2MPa) or low temperature (<-5℃), the system can reduce load, shut down, or activate protection logic, preventing compressor liquid slugging, pipe rupture, or refrigerant leakage. Integrated sensors respond faster and more accurately than separate components.

3. Simplified Installation and Reduced Leakage Risk: Traditional solutions require 2–3 installation points; the integrated design requires only 1, reducing O-rings and threaded connections, significantly lowering refrigerant leak probability. This is crucial for compliance with environmental regulations.

4. Supports Fault Diagnosis and Intelligent Management: Pressure-temperature data allows the ECU to model system status accurately, enabling early fault detection (blockages, refrigerant shortage, compressor efficiency loss). In connected vehicles, this data can be uploaded to the cloud for remote diagnostics and OTA optimization.

Industry Trends and Case Observations

In new energy vehicles, heat pump HVAC has become mainstream, driving rapid growth in demand for integrated temperature-pressure sensors. OEMs report a 15–25% reduction in overall AC system failure rate and a 10% faster cooling/heating response using integrated solutions. Many fuel vehicle upgrades also replace traditional separate sensors to meet stricter emission and energy efficiency regulations. Nexisense products have been widely deployed across multiple vehicle platforms, with customers noting exceptional stability under extreme temperature changes and long-term vibration.

Frequently Asked Questions (FAQ)

1. Main advantages over separate sensors?
Integration reduces interfaces, lowers leakage risk, saves space and cost, and provides more consistent pressure-temperature data.

2. Compatible refrigerants?
Supports mainstream refrigerants such as R134a, R1234yf, and R744 (CO₂), with materials verified for compatibility.

3. Performance in new energy vehicle heat pump systems?
High-precision and fast response improve winter heating efficiency and system stability.

4. How to select installation location?
High-pressure side usually at compressor outlet or condenser outlet; low-pressure side at evaporator inlet or return line, selected based on specific vehicle piping layout.

Conclusion

Automotive HVAC temperature-pressure integrated sensors represent a key trend toward integrated, intelligent thermal management. They address the limitations of traditional separate sensors and provide reliable support for efficiency, safety, and regulatory compliance. Nexisense continuously optimizes its sensors for engineering practicality and long-term reliability, supporting OEMs in building safer, more efficient HVAC systems. As new energy vehicles and smart cockpits grow, the application prospects for such integrated monitoring solutions are increasingly promising.