Refrigerant Pressure Sensor
WARNING: This page is about a different car, the 2006 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.
The refrigerant system is protected against excessively high or low pressures by the refrigerant pressure sensor, located on the refrigerant lines where they attach to the condenser. If the system pressure rises above or falls below the specifications, the refrigerant pressure sensor detects the pressure inside the refrigerant line and sends the voltage signal to the ECM. The ECM turns the A/C relay OFF and stops the compressor when pressure on the high pressure side detected by refrigerant pressure sensor is over about 2, 746 kPa (28 kg/cm2 , 398 psi) or below about 177 kPa (1.8 kg/cm2 , 26 psi).