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 zero volts. When the A/C refrigerant pressure is high, the signal value is near 5 volts. The A/C refrigerant pressure sensor prevents 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 413 psi (2850 kPa). The clutch will be enabled after the pressure decreases to less than 254 psi (1750 kPa).
• A/C pressure is less than 30 psi (204 kPa). The clutch will be enabled after the pressure increases to more than 32 psi (220 kPa).

If the PCM detects a failure in the A/C refrigerant pressure sensor or circuit, the class 2 message sent to the HVAC Control Module (IPM) will be invalid. The HVAC Control Module (IPM) will then send a request to the Radio for display of the "SERVICE A/C SYSTEM" that will be displayed on the DIC. The HVAC Control Module will also display A/C OFF on the module as long as the condition is present.