Refrigerant Pressure Sensor

WARNING: This page is about a different car, the 2009 Land Rover Range Rover, 2008 Land Rover Range Rover, and 2007 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 automatic temperature control (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 automatic temperature control (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 automatic temperature control (ATC) module uses the signal from the refrigerant pressure sensor to protect the system from extremes of pressure and to calculate air conditioning (A/C) compressor load on the engine for idle speed control. The automatic temperature control (ATC) module also provides a cooling fan request signal over the K bus to the instrument cluster. The cluster outputs this request to the engine control module (ECM) over the high speed controller area network (CAN) bus.

To protect the system from extremes of pressure, the automatic temperature control (ATC) module disengages the air conditioning (A/C) compressor clutch if the pressure:

Decreases to 1.9 ± 0.2 bar (27.5 ± 3 lbf/in² ): the automatic temperature control (ATC) module engages the air conditioning (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 automatic temperature control (ATC) module engages the air conditioning (A/C) compressor clutch again when pressure decreases to 23.5 ± 1 bar (341 ± 14.5 lbf/in² ).