General Information

General Information

Special tools, testers and auxiliary items required

• Vehicle Diagnostic Tester and the connection cable.

• A standard thermometer (for temperature measurements, if necessary a thermometer with 2 measuring probes for simultaneous measurement such as for temperature on the right and left)

Only for vehicles with mechanically driven A/C compressor and not for vehicles with a high voltage electrical system (hybrid vehicles)

• A/C cooling output, testing requirements, refer to => [ A/C Cooling Output, Testing Requirements ] A/C Cooling Output, Testing Requirements.

• Check cooling performance, refer to => [ Cooling Output, Checking ] Cooling Output, Checking.

• From MY 2010, these vehicles may have a Start/Stop System for specific engines as optional equipment. The setting on the Climatronic control module (J255) can prevent the Stop function. If, for example, "defrost" is selected, the stop function is not possible or will be interrupted and the engine will start. The same applies in the case of heating and cooling. The difference between the selected and actual temperature is greater than a specified value checked with the Vehicle Diagnostic Tester in "Guided Fault Finding".

• Vehicles with the Start/Stop System have an additional coolant recirculation pump (V50) ( water pump (V36) ) for the stop function, refer to => [ Coolant Pump ] Coolant Pump and the Vehicle Diagnostic Tester in "Guided Fault Finding".

• The coolant pump (water pump) is controlled not only when the "Start/Stop System" is on, but also when the engine is running and when the temperature is set to "warm" on the Climatronic control module ("HI" appears in the display on the A/C control head and in the MMI). The coolant pump (water pump is activated to support the engine coolant pump. Check using the Vehicle Diagnostic Tester in "Guided Fault Finding".

• The coolant pump (water pump) versions and activation differ depending on the version of the vehicle and production period. From MY 12 beginning with start of production, pumps that were controlled by a 500 Hertz signal (500 pulses per second) are being replaced by pumps that are controlled by a 100 Hertz signal depending on the engine. Pumps, controlled by a 100 Hertz signal, also have a diagnostic function and are controlled by the engine control module. Check for the correct allocation; refer to the Vehicle Diagnostic Tester in "Guided Fault Finding" and to the Parts Catalog.

• From MY 12 (introduction depending on the version of the vehicle), a revised fresh air blower control module (J126) (and fresh air blower (V2) , Climatronic control module, evaporator, expansion valves, motors and A/C are being used. Refer to the Parts Catalog and the Vehicle Diagnostic Tester in "Guided Fault Finding". Read all the information regarding these components. Refer to => [ A/C Unit and Air Intake Housing Overview, Basis A/C System ] A/C Unit and Air Intake Housing Overview, Basis A/C System.

• From the start of production through the change-over from MY 12, evaporators approximately 40 mm (1.6 in.) wide (block depth) are being installed (air conditioner part number "8K_ 820 005"). From MY 12, as a running change and depending on the version of the vehicle, an approximately 50 mm (2 in.) wide evaporator (block depth) is being installed (air conditioner part number "8T_ 820 005"). Pay attention to the correct allocation of the evaporator expansion valve (there are different versions). Refer to the Parts Catalog.