Refrigerant Pressure Sensor

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The refrigerant pressure sensor is located in the high pressure refrigerant line between the condenser and the thermostatic expansion valve.

The Automatic Temperature Control Module (ATCM) provides a 5v reference voltage to the refrigerant pressure sensor and receives a return signal voltage related to system pressure.

The ATCM uses the signal from the refrigerant pressure sensor to protect the refrigerant system from extremes of pressure and to calculate the Air Conditioning (A/C) compressor load on the engine. The ATCM transmits the A/C compressor load value to the PCM, via the High Speed (HS) Controller Area Network (CAN) Power Mode Zero bus, Body Control Module/Gateway Module (BCM/GWM) and HS CAN Powertrain bus, for use in controlling the speed of the engine cooling fan.

To protect the system from extremes of pressure, the ATCM will disengage the clutch to switch off the A/C compressor, if the pressure:

Decreases to 1.9 ± 0.2 bar (27.5 ± 3 lbf/in² ); the ATCM loads the A/C compressor again when the pressure increases to 2.8 ± 0.2 bar (40.5 ± 3 lbf/in² ).
Increases to 33 ± 1 bar (479 ± 14.5 lbf/in² ); the ATCM loads the A/C compressor again when the pressure decreases to 23.5 ± 1 bar (341 ± 14.5 lbf/in² ).

NOTE: If the evaporator is faulty the A/C compressor is disengaged.