A/C Refrigerant Pressure Sensor
WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The A/C refrigerant pressure sensor is a 3-wire piezoelectric pressure transducer. A 5-volt reference, low reference, and signal circuits enable the sensor to operate. The A/C pressure signal can be between 0-5 volts. When the A/C refrigerant pressure is low, the signal value is near 0 volts. When the A/C refrigerant pressure is high, the signal value is near 5 volts. The ECM converts the voltage signal to a pressure value.
The A/C refrigerant pressure sensor protects the A/C system from operating when an excessively high pressure condition exists. The ECM disables the compressor clutch if the A/C pressure is more than 3234 kPa. The clutch will be enabled after the pressure decreases to less than 1931 kPa.