REFRIGERANT PRESSURE SENSOR CONSTRUCTION
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• A capacitance type A/C pressure switch, which converts refrigerant pressure into a linear electric signal, has been adopted.
• Consists of a pressure detecting part and signal processing part.
• The pressure detecting part is a variable capacity condenser which changes capacitance according to the pressure.
• The signal processing part detects the capacitance of pressure detecting part, converts it to voltage, then outputs it to the PCM.
• When pressure is abnormal, the PCM cuts the A/C relay thereby stopping the A/C compressor.
Pressure Detecting Part
• There is a clearance between the movable ceramic diaphragm and the ceramic base, and each side has an electrode.
• When pressure is applied from the ceramic diaphragm side, the ceramic diaphragm deforms, and the clearance between the electrodes changes. As a result, capacitance is changed and pressure is detected.