Fresh Air Blower Control Module (J126)

Fresh Air Blower Control Module (J126)

• There are different versions of the replacement fresh air blower control module (for example, versions - A - and - B -). Pay attention to the correct allocation. Refer to the Parts Catalog.






• From start of production through MY 12, version - A - was installed. From MY 12, version - A - was changed to version - B - (the time when the change-over took place depends on the version of the vehicle). Version - B - also has a seal - C -. Refer to the Parts Catalog.

• From MY 12, (introduction depends on the version of the vehicle) a revised fresh air blower control module - B - (and fresh air blower (V2) , Climatronic control module (J255) and A/C unit with part number "8T_ 820 005") are being used. The air intake manifold, along with the fresh air blower control module and the A/C unit is also revised. Be sure to use the correct version and allocation. Refer to the Parts Catalog and the Vehicle diagnostic tester in "Guided Fault Finding".

• The fresh air blower control module does not control the fresh air blower if the Climatronic control module allocation or adaptation to fresh air blower module (part number 8K0 820 521 or 8T0 820 521) is not according to the specification. In this case a fault is not always stored in the DTC memory even though the fresh air blower activation is not OK. Make sure the Climatronic control module adaptation is correct. Refer to the Parts Catalog and to the Vehicle diagnostic tester in "Guided Fault Finding".

• There is a label - A - on the outside of the A/C unit with a part - B - that tells which version is installed. Refer to the Parts Catalog.






• The part number - B - on the decal - A - can be read when the CD changer is removed (depending on the vehicle equipment level). Refer to the Electronic Parts Catalog (ETKA).

• When the ignition is on and the fresh air blower (V2) is set at "Plus", the fresh air blower control module interconnects (for example, on version - A -) from contact "4" on terminal - C - to contact "1" on connector - B -. Fresh Air Blower speed is regulated by Fresh Air Blower Control Module via the ground connection between terminal "2" connector - B - and terminal "3" of connector - C -. Refer to the Vehicle diagnostic tester in "Guided Fault Finding".






• As a running change in MY 10, gasoline engines that can run on bioethanol (Flex Fuel Vehicles) were introduced, which currently have an auxiliary heater heating element (Z35). Refer to => [ Auxiliary Heater Heating Element (Z35), Testing ] Testing and Inspection.

• Currently an auxiliary air heater heating element is installed for vehicles with a high voltage system (hybrid vehicles) and a gasoline engine. Refer to => [ Auxiliary Heater Heating Element (Z35), Testing ] Testing and Inspection.

• The activation of the auxiliary heater heating element occurs for vehicles with a gasoline engine from the Climatronic control module (J255) via the local Data bus (controlled using the same outlet and also using the fresh air blower control module (J126) ) on the auxiliary air heater control module (J604). Check the fresh air blower control module or the fresh air blower and also the auxiliary air heater control module when complaints arise for these vehicles. Refer to the Vehicle diagnostic tester in "Guided Fault Finding".

• Make sure the auxiliary air heater heating element is working. Refer to => [ Auxiliary Heater Heating Element (Z35), Testing ] Testing and Inspection.

Removing

- Move the passenger seats as far back as possible.

- Turn off the ignition.

- Remove the glove compartment.

- Disconnect the connector - A - and - B -.






- Remove the screws - C -.

Heat sink on Fresh Air Blower Control Module (J126) may be hot.

- Remove the Fresh Air Blower Control Module - D - from the air intake housing.

Installing

Installation is carried out in the reverse order while observing the following.

- Switch on the ignition.

- Check the Climatronic control module (J255) DTC memory and erase any displayed malfunctions if necessary using the Vehicle diagnostic tester in "Guided Fault Finding".

- To check the function, perform an output Diagnostic Test Mode (DTM) on the A/C system using the Vehicle diagnostic tester in "Guided Fault Finding".