Notes On Components Outside Passenger Compartment, All Versions

If there is a malfunction in the A/C system, first check the DTC memory of the Climatronic Control Module -J255- A/C display and control head, using the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function. If a different control module displays a message to read the DTC memory, also read the DTC memory for this control module (for example, the Vehicle Electrical System Control Module -J519-, the Comfort System Central Control Module -J393-); certain A/C system components (for example, the A/C Compressor Regulator Valve -N280-, the A/C Pressure/Temperature Sensor -G395-) are no longer activated directly by the Climatronic Control Module -J255- A/C display and control head and their measuring values are no longer evaluated directly by the Climatronic Control Module -J255- A/C display and control head.

If no fault is displayed, read the measured value block for the Climatronic Control Module -J255- A/C display and control head and activate the potentially defective component with the "output diagnosis test mode" function, using the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function.

The function "electrical testing" is not described in this repair manual. Perform an electrical test via the "Guided Fault Finding"  function, here can notes also be found on the functions which should be tested, using the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function.

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, using the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function.

The electrical test of the different actuators is described in Guided Fault Finding, using the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function.

Repair work on refrigerant circuit are described. Refer to REFRIGERANT CIRCUIT .

Components on the outside of the passenger compartment, which are only present for vehicles with a high voltage system (hybrid vehicles) or those for vehicles without a high voltage system vary. Refer to OVERVIEW - COMPONENTS OUTSIDE OF PASSENGER COMPARTMENT .

For removing and installing the coolant hoses from connections to A/C heater core. Refer to HEATER CORE, REMOVING AND INSTALLING .

Incorporation of the A/C heater core in the engine coolant circuit. Refer to CONNECTION DIAGRAM - COOLANT HOSES .

Depending on the vehicle date of manufacture, the connecting points may be installed in the refrigerant lines on certain versions (not planned at this time, introduction not yet finalized). As with connections on various components, these connection points may only be loosened and opened when the refrigerant circuit is empty. Refer to OVERVIEW - REFRIGERANT CIRCUIT and A/C SYSTEM, GENERAL INFORMATION (Refrigerant R134a Servicing, A/C System, General Information).

For vehicles with a 6-Cylinder gasoline engine and other engines with certain optional equipment (such as vehicles with the Start/Stop system) but without a "Parking Heater", a Coolant Recirculation Pump -V50- (a Water Pump -V36-) is installed. Refer to OVERVIEW - COMPONENTS OUTSIDE OF PASSENGER COMPARTMENT => Component Group "3" and COOLANT PUMP, REMOVING AND INSTALLING .

Depending on the version of the Climatronic Control Module -J255- A/C display and control head, the Coolant Recirculation Pump -V50- may be referred to as Water Pump -V36- in Guided Fault Finding, using the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function.

The Coolant Recirculation Pump -V50- (Water Pump -V36-) version and activation differ depending on the vehicle version and production period. From MY 2012 as a running change, the pumps installed from the start of production, which were activated via a 500 Hertz signal (500 pulses per second), are being replaced by pumps that are activated by a variable (100 to 500 Hertz) signal depending on the engine. Pumps that are activated by a variable signal are also equipped with a diagnostic function and are activated mostly via the respective engine control module. Therefore, ensure the correct allocation (only the allocated pump can be activated), using the Vehicle Diagnostic Tester in the "Guided Fault Finding"  function, refer to appropriate SYSTEM WIRING DIAGRAM .