OBD and A/C System, Checking

OBD and A/C System, Checking

• The function electrical testing is not described in this Repair Manual. Perform electrical testing via Guided Fault Finding function, here can also be found notes on the functions which should be tested using Vehicle Diagnosis, Testing and Information System VAS 5051 in "Guided Fault Finding".

• Temperature-dependent resistance values of the various temperature sensors are stored in one table, these can be called up via the "Guided Fault Finding" function on the Vehicle Diagnosis, Testing and Information System VAS 5051 in "Guided Fault Finding".

• The Climatronic Control Module (J255) and Rear A/C Display Control Head (E265) are available in different versions. Pay attention to precise assignment on replacement. Refer to the Electronic Parts Catalog.

• A/C system OBD is performed in the Guided Fault Finding function with the Vehicle diagnosis, testing and information system in the "Guided Fault Finding" function.

• Climatronic control module Comfort version cannot always be exchanged in the familiar way, as soon as Climatronic control module Comfort version has been adapted once in a vehicle, the component protection takes effect. This function is currently not on the Basis version). Component protection can only be canceled by entering specific vehicle data using Vehicle Diagnosis, Testing and Information System VAS 5051 in "Guided Fault Finding" function.

• If a Climatronic control module is installed on the Comfort system with active component protection is the installed in a different vehicle, only the functions necessary for vehicle safety can be selected. Comfort functions can no longer be selected. Refer to vehicle diagnosis, testing and information system VAS 5051 in the "Guided Fault Finding" function.

• If a Climatronic control module (or rear A/C display control head) is to be replaced, check the coding (Climatronic control module) and adaptation (front Climatronic control module and rear A/C display control head) before removing with the "Replace control module" function of Guided Fault Finding for this control head using Vehicle diagnosis, testing and information system VAS 5051 in the "Guided Fault Finding" function.

• On vehicles equipped with rear A/C system, the DTC "Check DTC memory of Climatronic Control Module" is entered in rear A/C display control head for certain malfunctions at the front A/C system. After erasing the DTC memory, check the Climatronic control module and the DTC memory of the rear A/C display control head. Refer to Vehicle Diagnosis, Testing and Information System VAS 5051 in "Guided Fault Finding".

• Pressing and holding the buttons on the Climatronic control module or rear A/C display control head for an extended period of time (for example, setting an object down on them) can cause an entry in the DTC memory due to stuck buttons. If necessary, check the function of the buttons and erase the DTC memory if no malfunction is found.

• Certain malfunctions can be erased only after starting engine (for example, "ignition off time period signal" after replacing Instrument Cluster Control Module (J285) ). If a malfunction cannot be erased, start engine and let it run for 1 minute before checking and erasing DTC memory again.

• The refrigerant temperature sensor (G454) was discontinued as of November 2007 as a running change. On vehicles with the Comfort A/C system, make sure the Climatronic control module for the Comfort A/C system is installed. Vehicles with a 6 cylinder TDI engine or an 8 cylinder engine but without a refrigerant temperature sensor may only have the Comfort front control and display unit installed (part number 4L0 820 043, beginning with index letter K). Refer to the Electronic Parts Catalog.

• Starting in November 2007 the Comfort has an updated Fresh Air Blower Control Module (J126) (an updated Climatronic control module for the Comfort A/C system and an updated Fresh Air Blower (V2) ) and an updated air intake housing. Refer to => [ Fresh Air Blower Control Module (J126) ] Fresh Air Blower Control Module (J126) and Electronic Parts Catalog.