General Information

Automatic Climate Control System, On Board Diagnostic (OBD)

NOTE:
- There are different versions of the Climatronic Control Module -J255- and Rear A/C Control Head (Climatronic) -E265-. Pay attention to precise assignment on replacement.
- Air conditioner On Board Diagnostic (OBD) is to be performed by way of "Guided Fault Finding" function using vehicle diagnostic, testing and information system VAS 5051.
- Control and display units can no longer be interchanged between vehicles in the familiar manner. The component protection feature is activated as soon as a Climatronic Control Module -J255- has been adapted to a vehicle.
- Component protection can only be cancelled by entering certain vehicle data.
- If a front control and display unit with active component protection (anti-theft system) is installed in a different vehicle, the functions required for vehicle security can still be selected, but not the convenience functions.
- If Climatronic Control Module -J255- or Rear A/C Control Head (Climatronic) -E265- is to be replaced, check coding (of Climatronic Control Module -J255-) and adaptation (of Climatronic Control Module -J255-/Rear A/C Control Head (Climatronic) -E265-) by way of "Control unit replacement" function in Guided Fault Finding routine for appropriate control and display unit prior to removal.

Malfunction Detection
Malfunctions occurring in monitored sensors or components are stored in DTC memory together with an indication of the type of malfunction.

The first step in the troubleshooting process is always to start On Board Diagnostic (OBD) and check the malfunctions stored. This can be implemented by way of the following:
- Vehicle diagnostic, testing and information system VAS 5051
- Vehicle system tester VAS 5052

The malfunction information displayed is used in conjunction with a malfunction table (containing information on possible causes of trouble) to perform pin-pointed repair measures.

Notes on malfunction indication:
- If a malfunction condition exists for longer than a pre-determined period, the malfunction is stored as being static. If the malfunction condition is then no longer detected for a predetermined period, the malfunction is reclassified as being a sporadic malfunction. This process is constantly repeated. Sporadic malfunctions are additionally identified as such by /SP on the display.
- A sporadic malfunction is erased automatically if it no longer occurs for a pre-determined period.

At present, the On Board Diagnostic (OBD) functions available can only be implemented using the vehicle diagnostic, testing and information system VAS 5051 and the vehicle system tester VAS 5052.

On Board Diagnostic (OBD) is not restricted to storage, checking, cancellation and output Diagnostic Test Mode (DTM). It also offers basic setting, control module identification, adaptation and coding functions.