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

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

• The cooling performance cannot be checked with A/C Pressure/Temperature Sensor removed. The Climatronic control module (J255) does not switch on the A/C compressor. "Read measured values" using 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.

• If a malfunction is detected in the signal from the A/C Pressure/Temperature Sensor, a malfunction is entered in the event memory of the Vehicle electrical system control module and the Climatronic control module. When reading out the event memory of the Climatronic control module, you will be prompted to query the event memory of the Vehicle electrical system control module using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• 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 (ETKA).

• After switching off the A/C compressor in this vehicle, it may take a relatively long time for the pressure on the high pressure side to decrease. This is because the expansion valve is cold and the pressure on the low pressure side increases quickly after shutting the compressor off, then the expansion valve closes and the refrigerant flows slowly to the low pressure side.

Test Sequence






- Remove the lock carrier cover.

- Disconnect the electrical harness connector - A -.

- Check the ground and positive connection to the connector - A -.

- Check the connection and the function of the A/C Pressure/Temperature Sensor using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

Assignments for the 3-pin harness connector on the A/C pressure/temperature sensor:

1. Ground

2. Signal output - via the local Data bus to the Vehicle electrical system control module (J519)

3. Terminal 75 (positive)


• 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.