A/C Pressure Sensor

WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The A/C 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 0-5 volts. When the A/C refrigerant pressure is low, the signal value is near zero volts. When the A/C refrigerant pressure is high, the signal value is near 5 volts.

The A/C pressure sensor protects the A/C system from operating when an excessively high or low pressure condition exists. The Engine Control Module (ECM) disables the compressor clutch under the following conditions:

A/C high side pressure is more than 427 psi (2945 kPa). The clutch will be enabled after the high side pressure decreases to less than 300 psi (2069 kPa).
A/C low side pressure is less than 31 psi (210 kPa). The clutch will be enabled after the low side pressure increases to more than 37 psi (258 kPa).