Refrigerant Pressure Sensor / Switch: Description and Operation

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 between 0-5 volts. When the A/C refrigerant pressure is low, the signal value is near 0 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 engine control module (ECM) or powertrain control module (PCM) disables the compressor clutch under the following conditions:
The A/C high side pressure is more than 2929 kPa (495 psi). The clutch will be enabled after the high side pressure decreases to less than 1376 kPa (200 psi). A/C low side pressure is less than 2706 kPa (39 psi). The clutch will be enabled or will allow engagement again after the low side pressure increases to more than 2941 kPa (43 psi).