A/C Pressure Sensor

The Powertrain Control Module (PCM) monitors the high side refrigerant pressure via an A/C refrigerant pressure sensor. 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 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 refrigerant pressure sensor protects the A/C system from operating when an excessively high or low-pressure condition exists. The PCM disables the compressor clutch under the following conditions:

• A/C pressure is more than 432 psi (2979 kPa). The clutch enables after the pressure decreases to less than 219 psi (1510 kPa).
• A/C pressure is less than 27 psi (186 kPa). The clutch enables after the pressure increases to more than 30 psi (207 kPa).