Test Requirements

Test Requirements

Special tools, testers and auxiliary items required

• Diagnostic Operation System (VAS 5051 A) (or Vehicle Diagnosis & Service System (VAS 5052) )

• On vehicles with Basic version A/C system, a conventional thermometer (for measuring temperature, if necessary use a thermometer with 2 measuring probes for simultaneous measurement for example, temperature on right and left sides).

• On vehicles with Comfort version A/C system, the specified temperatures themselves can be measured or read out via the "Read measuring value block" function using Vehicle Diagnosis, Testing and Information System VAS 5051 in "Guided Fault Finding".

• On vehicles with a rear heating & A/C unit, cooling performance in front heating & A/C unit must be checked first. only when this is OK can the cooling performance of rear heating & A/C unit can be checked => [ Rear A/C System, Testing Cooling Performance ] Rear A/C System, Testing Cooling Performance.

Test Requirements

• Ambient temperature greater than 15 °C (59 °F).

• Radiator and condenser are clean (if necessary clean).

• Compressor drive ribbed belt is OK and correctly tensioned and belt pulley actually drives the compressor (on 6 cylinder TDI engine), refer to => [ Compressor, Removing and Installing on Bracket ] Compressor, Removing and Installing on Bracket.

• Compressor drive unit is mounted correctly, compressor is actually driven (on 8 cylinder FSI engine), refer to=> [ Compressor ] Compressor.

• All air ducts, covers and seals are OK and properly installed.

• Air flow through dust and pollen filter is not impaired by soiling (removing and installing dust and pollen filter, refer to => [ Dust and Pollen Filter ] Service and Repair).

• Vehicle not exposed to sunlight.

• Engine is warm.

• DTC memory of Climatronic Control Module (J255) (and of Rear A/C Display Control Head (E265) ) has been checked and erased, basic setting has been performed using Vehicle Diagnosis, Testing and Information System VAS5051 in the "Guided Fault Finding" function.

• Coding of Climatronic control module has been checked using Vehicle Diagnosis, Testing and Information System VAS 5051 in "Guided Fault Finding" function.

• Adaptation of Climatronic control module (and of rear A/C display control head) was checked using Vehicle Diagnosis, Testing and Information System VAS5051 in the "Guided Fault.

• All vents (of instrument panel, in rear center console and in B and C pillars) have been opened. (for vehicles with rear A/C system).

• All instrument panel vents open (On vehicles with Comfort version A/C system without rear A/C system, vents in rear center console and in B pillars closed).

• The hood is closed.

• The following are set on Climatronic control module or on MMI (Multi Media Interface) (Refer to Owner's Manual and Owner's Manual / Infotainment/MMI):

- Auto operating mode (on Comfort version A/C system)

- Temperature preselect LO (for driver's and front passenger's side on Comfort version A/C system) or temperature rotary actuator at cold stop (for Basic version A/C system)

- Compressor switched on (function Econ is not active).

- Rotary switch for fresh air blower speed in position 4 (on Basic version A/C system)

• Settings on rear A/C display control head (if present, optional equipment)

- Operating mode Auto for air distribution.

- Temperature preselect LO (for left and right sides).

• Functions with engine running:

- Coolant Fan (V7) is running or is switched on when a certain pressure in refrigerant circuit is exceeded (speed depends on pressure in refrigerant circuit and on engine coolant temperature).

• At this time, Coolant Fan always operates while compressor is switched on, however it may be in the future that it is switched on only during cooling performance testing as soon as a certain pressure in refrigerant circuit is exceeded, depending on version of Climatronic control module (activation of Coolant Fan is displayed in the measuring value block of Vehicle Diagnosis, Testing and Information System VAS5051 in the "Guided Fault Finding" function).

- Fresh Air Blower (V2) runs at maximum speed.

- Front A/C system switches to air recirculation mode (fresh air intake is closed approximately 1 minute after starting vehicle) and air is drawn in from front passenger's footwell (by Fresh Air Blower).

• At this setting (maximum cooling output), Coolant Pump (V50) is not actuated by the Climatronic Control Module. However it may be switched on by the respective Engine Control Module (ECM), depending on engine and on the current coolant temperature.

• At this time, the Coolant Pump is not installed on vehicles with 6 cylinder gasoline engine without parking heater optional equipment. On these vehicles, Coolant Pump (V36) is installed to circulate the coolant. Coolant Pump (V36) may also run if A/C system does not require heat output (for example, at setting for maximum cooling output), it may then be actuated by ECM depending on the coolant temperature.

- If one of these test requirements is not fulfilled, check the DTC memory for the Climatronic control module, perform output diagnostic test mode and read the measured value block using vehicle diagnosis, testing and information system VAS5051 in the "Guided Fault Finding" function.