A/C Pressure Sensor

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The A/C refrigerant pressure sensor is a 3 wire piezoelectric pressure transducer. The Powertrain Control Module (PCM) monitors the high side refrigerant pressure through the A/C refrigerant pressure sensor. When the pressure is high the signal voltage is high. When the pressure is low the signal voltage is low. When pressure is high the PCM commands the cooling fans on. When pressure is too high or too low the PCM will not allow the A/C compressor clutch to engage. 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 (see appropriate HEATING & AIR CONDITIONING article for pressure limits specific to model):

A/C pressure is more than 430-432 psi (2968-2979 kPa). The clutch will be enabled after the pressure decreases to less than 219 psi (1510 kPa).
A/C pressure is less than 27-35 psi (186-255 kPa). The clutch will be enabled after the pressure increases to more than 30 psi (207 kPa).