A/C Pressure Sensor
WARNING: This page is about a different car, the 2001 Chevrolet Malibu and 2000 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
An electronic pressure sensor is mounted in-line between compressor and condenser. Pressure sensor output signal is sent to Powertrain Control Module (PCM). Signal is variable and is dependent upon pressure inside refrigerant line. PCM will stop compressor operation if pressure exceeds 428 psi (30.1 kg/cm2 ), or is less than 43 psi (3.0 kg/cm2 ). Higher pressures result in higher voltage output signal to PCM. PCM uses this signal to increase idle speed to compensate for A/C load and control cooling fan operation.