High Pressure Sensor / Switch: Testing and Inspection

A/C Pressure/Temperature Sensor (G395), Checking Pressure Signal

• The coolant performance cannot be checked when the A/C pressure/temperature sensor is removed, the Climatronic control module (J255) , does not activate the A/C compressor. Check using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• To check the measured values of the A/C pressure/temperature sensor use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• The A/C pressure/temperature sensor exchanges information with the vehicle electrical system control module (J519) via a local data bus. The vehicle electrical system control module transmits the data via the data bus to the Climatronic control module.

• The temperature measured by the A/C pressure/temperature sensor differs from the actual refrigerant temperature because of the design of the A/C pressure/temperature sensor and its installation location. Because of this, it is not currently evaluated and is not used to regulate the A/C system.

• Only the A/C pressure/temperature sensor may be installed in this vehicle. Refer to Electronic Parts Catalog.

• On this vehicle, it may take awhile until the pressure on the high pressure side comes down after the A/C compressor is switched off. The expansion valve(s) is/are cold and the pressure on the low pressure side increases quickly after deactivation, the expansion valve(s) closes/close and the refrigerant can flow only slowly on the low pressure side.

Preparation

- Switch off ignition.

- Remove front noise insulation.

- Vehicles with 8 cylinder TFSI engine, remove the front bumper cover.

- Disconnect the electrical connector - A -.






Routing For The 3-Pin Connector On The A/C Pressure/Temperature Sensor - A -.

1. Ground

2. Signal output - via the local Data bus to the vehicle electrical system control module

3. Terminal 75 (positive)


Test sequence:

- Switch on the ignition.

- Check the ground and plus connection to the terminal - A -.

- Check the connection and the function of the A/C pressure/temperature sensor as described in the Guided Fault Finding using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• The A/C compressor ( A/C compressor regulator valve (N280) ) is not actuated when the connector - A - is disconnected.

• The A/C pressure/temperature sensor is an electronic control module that exchanges information with the vehicle electrical system control module via a local data bus. Check using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.