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

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 switch on the A/C compressor. Check using the Vehicle diagnostic tester in "Guided Fault Finding".

• Check the refrigerant pressure sensor and the refrigerant temperature measured values using the Vehicle diagnostic tester in "Guided Fault Finding".

• 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 A/C pressure/temperature sensor design and its component location. Because of this, it is not currently evaluated and is not used to regulate the A/C system.

• Only A/C pressure/temperature sensor may be installed for this vehicle. Refer to Electronic Parts Catalog (ETKA).

• After switching off the A/C compressor on this vehicle, it may take a long time until the pressure on the high pressure side (the expansion valve is "cold" and the pressure on the low pressure side increases quickly after switching off, the expansion valve closes and the refrigerant can flow slowly on the low pressure side.

Preparation

- Turn off the ignition.

- Remove the upper cover on the lock carrier 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 (J519)

3. Terminal "75" (positive)


Test sequence:

- Switch on the ignition.

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

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

• 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 over which a local Data bus exchanges information with the vehicle electrical system control module (J519). Refer to the Vehicle diagnostic tester in "Guided Fault Finding".