Refrigerant Pressure Sensor

Courtesy of JAGUAR CARS, INC.

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

The ECM supplies a 5 V reference feed to the pressure sensor and receives a return signal voltage, between 0 V and 5 V, related to system pressure. The ECM uses the signal from the sensor to protect the refrigerant system from extremes of pressure.

If the pressure within the refrigerant system exceeds the minimum or maximum pressure limits, the ECM will;

disable the A/C compressor (TD4 vehicles)
reduce A/C compressor displacement (i6 vehicles).

If a reduction in A/C compressor displacement fails to bring the system back into it's optimum pressure range, the i6 ECM will disable the A/C compressor.

The ECM constantly sends a refrigerant system pressure signal to the ATC module. The signal is transmitted from the ECM to the Central Junction Box (CJB) over the high speed CAN bus. The CJB acts as a gateway and provides the pressure signal to the ATC module over the medium speed CAN bus.

If the pressure within the refrigerant system rises above its maximum pressure limit, the ATC module will increase the amount of recirculated air entering the cabin. This helps lower the pressure within the refrigerant system and thus helps to avoid having to disable the A/C compressor.