Refrigerant Pressure Sensor

The refrigerant pressure sensor provides the ATCM with a pressure input from the high-pressure side of the refrigerant system. The refrigerant pressure sensor is located in the refrigerant line between the A/C condenser and the thermostatic expansion valve.

The ATCM supplies a 5V reference voltage to the refrigerant pressure sensor and receives a return signal voltage, between 0V and 5V, related to system pressure.

The ATCM uses the signal from the pressure sensor to protect the refrigerant system from extremes of pressure. The ATCM transmits the A/C pressure, along with the compressor drive current value, to the Body Control Module/Gateway Module (BCM/GWM) assembly on the HS CAN comfort systems bus. These signals are broadcast to the Powertrain Control Module (PCM) on the HS CAN powertrain systems bus to allow it to calculate the torque being applied to the engine by the compressor.

To protect the system from extremes of pressure, the ATCM sets the A/C compressor to the minimum flow position if the pressure:

• Decreases to 2.1 ± 0.2 bar (31.5 ± 3 lbf/in² ). The ATCM loads the A/C compressor again when the pressure increases to 2.3 ± 0.2 bar (33.4 ± 3 lbf/in² )
• Increases to 31 ± 1 bar (450 ± 14.5 lbf/in² ). The ATCM loads the A/C compressor again when the pressure decreases to 26 ± 1 bar (377 ± 14.5 lbf/in² ).

The ATCM also uses the signal from the refrigerant pressure sensor to request engine cooling fan duty from the PCM via the BCM/GWM assembly, using the HS CAN comfort and powertrain systems buses.

In addition, the ATCM calculates the amount of torque used to drive the A/C compressor using inputs from the refrigerant pressure sensor and the Ambient Air Temperature (AAT) sensor. This information is also transmitted to the PCM via the BCM/GWM assembly on the HS CAN comfort and powertrain systems buses.