Refrigerant Pressure Sensor / Switch: Description and Operation

AIR TEMPERATURE

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 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 2850 kPa (413 psi). The clutch will be enabled after the pressure decreases to less than 1750 kPa (254 psi).
- A/C pressure is less than 204 kPa (30 psi). The clutch will be enabled after the pressure increases to more than 220 kPa (32 psi).

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.