What is the automobile air conditioning pressure sensor
The automotive air conditioning pressure sensor is the core component of the refrigeration system. Its main function is to monitor the refrigerant pressure in the air conditioning pipeline in real time, ensure the safe operation of the compressor, and work with other components to accurately control the start and stop of the cooling fan and compressor. It is usually installed in the air conditioning high pressure pipe in the engine compartment and transmits the collected pressure data to the engine ECU or a specialized air conditioning control unit. When the ECU receives a normal pressure signal, it starts the compressor and cooling fan; If an abnormal pressure signal is detected, immediate measures are taken to prevent air conditioning equipment such as compressors from starting, thereby protecting the entire refrigeration system.
Air conditioning pressure sensor usually adopts three-wire system design, its control mode includes analog signal, Lin bus and duty cycle control three types. To measure the pressure sensor of an air conditioner, use a multimeter to measure the power cable, ground cable, and signal cable of the sensor. In normal cases, the power cable is 5V or 12V, the ground cable is 0V, and the signal cable fluctuates in the range of 0.5V to 4.5V or 1V to 5V. If the measured value is significantly different from the standard value, it may mean that the sensor is damaged or there is a virtual connection in the harness.
The air conditioning pressure sensor plays a vital role in the automobile refrigeration system. If the sensor fails, it may lead to no cooling effect in the car, the compressor cannot work, or frequent start and stop problems. Therefore, regular inspection and maintenance of the air conditioning pressure sensor is an important measure to ensure the normal operation of the automobile air conditioning system.
The operating principle of the automotive air conditioning pressure sensor is based on pressure measurement, usually consisting of a thin film and a grid of resistors. When the pressure in the automotive air conditioning system changes, the pressure of the measured medium will be transmitted to the film in the sensor. The film deforms under the action of pressure, resulting in the corresponding resistance change of the resistance grid on the film. This resistance change can be detected and read by a circuit connected to a dashboard or other control unit.
The application of automotive air conditioning pressure sensors in automotive air conditioning systems includes many types, each type has its specific function and installation location. For example, a high voltage switch is installed on the condenser inlet pipe to adjust the speed of the fan motor and ensure that the condenser pressure is kept within a safe range. When the condensing pressure is lower than 1.51 mpa, the fan maintains low speed operation. Once the pressure exceeds 1.5 mpa, the fan accelerates to high speed. In addition, a double temperature switch is located next to the condenser and combines the high pressure switch with the engine coolant temperature to control the operation of the condensing fan motor. When the coolant temperature is between 95 and 102 ° C, the fan rotates at a low speed; When the temperature exceeds 102 ° C, the fan operates at high speed.
The role of automotive air conditioning pressure sensor in automotive air conditioning system is to protect the system and improve efficiency. They prevent excessive pressure from causing damage to components by monitoring pressure changes within the system. For example, when the high pressure line pressure is below 0.2 mpa or above 3.2 mpa, the compressor's electromagnetic clutch is disconnected to protect the system; The clutch remains engaged between 0.22 and 3.2 mpa. In addition, the external temperature switch disconnects the compressor electromagnetic clutch when the temperature is below 5 ° C, preventing the air conditioning compressor from working at low temperatures.
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