Refrigerant Pressure Sensor

WARNING: This page is about a different car, the 2006 Land Rover Range Rover. However, it is still accessible from the selected car via links, so may be relevant.

The refrigerant pressure sensor provides the ATC module 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 condenser and the thermostatic expansion valve.

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

The ATC module uses the signal from the refrigerant pressure sensor to protect the system from extremes of pressure and to calculate A/C compressor load on the engine for idle speed control. The ATC module also transfers the pressure value to the engine control module ECM, via the K bus, instrument cluster and controller area network CAN bus, for use in controlling the speed of the engine cooling fan.

To protect the system from extremes of pressure, the ATC module disengages the A/C compressor clutch if the pressure:

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