Refrigerant Pressure Sensor / Switch: Description and Operation

The PCM uses the A/C pressure sensor to monitor the high pressure side of the A/C system. The PCM supplies the sensor with a 5 volt reference and a ground. The sensor returns a signal voltage relative to the A/C refrigerant pressures. The PCM uses this information to turn ON the engine coolant fans when the A/C pressure is too high. If the sensor indicates that the A/C refrigerant pressure is too high or too low, the PCM will disengage the A/C compressor. If the PCM detects an A/C pressure sensor signal above or below the possible range of the sensor, DTC P0532 or DTC P0533 will set.

The A/C pressure sensor is mounted on the discharge line of the A/C compressor hose assembly. The sensor's output to the powertrain control module is variable and is dependent upon pressure inside the line. A higher pressure results in a higher voltage output.

A/C pressure is constantly monitored in order to allow the A/C clutch to disengage due to aberrant pressures:
^ If the pressures are above 2968 kPa (430 psi)
^ If the pressures are below 255 kPa (35 psi)