Initial Inspection and Diagnostic Overview

Cooling Performance Test Requirements

Special tools, testers and auxiliary items required

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

• Standard thermometer for temperature measurements, if necessary a thermometer with 2 measuring probes for simultaneous measurement for temperature at right and left

• Ambient temperature greater than 15 °C

• Clean radiator and condenser clean if necessary

• Compressor drive ribbed belt is OK and correctly tensioned and belt pulley actually drives the compressor on vehicles with 6 cylinder engine, 8 cylinder MPI engine, 8 cylinder diesel engine or 12 cylinder engine.

• Compressor drive unit is mounted correctly, compressor is actually driven on vehicles with 8 cylinder. FSI engine or 10 cylinder engine. Refer to=> [ Compressor Drive Unit ] Compressor Drive Unit.

• All air ducts, covers and seals OK and properly fitted

• Air flow through dust and pollen filter not obstructed by dirt.

• Vehicle not exposed to sunlight

• Engine is warm

• The DTC memory for the Climatronic Control Module (J255) front A/C control head and the Rear A/C Control Head (Climatronic) (E265) was checked and erased, basic setting was performed and the front control head coding was checked vehicle diagnosis testing and information system VAS 5051 in the "Guided Fault Finding" function.

• Adaptation of front A/C control head Climatronic Control Module (J255) and of Rear A/C Control Head (Climatronic) (E265) was checked vehicle diagnosis testing and information system VAS 5051 in the "Guided Fault Finding" function.

• All instrument panel vents open

• Hood closed

• Settings on front A/C control head Climatronic Control Module (J255) or on MMI (Multi Media Interface).

- Operating mode "Auto".

- Temperature selection "LO" for driver's and passenger's side.

- The compressor is on the "Econ" function is not active in the MMI, A/C mode is on.

• Functions with engine running:

- Coolant Fans (V7) is running, speed depends on pressure in refrigerant circuit and engine temperature.

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

- The A/C system switches to recirculation mode approximately 1 minute after starting the engine, the fresh/back pressure doors close and the recirculation door opens, the Fresh Air Blower (V2) extracts air from the passenger compartment under the instrument panel.

- No operation of Coolant Pump (V50).

- Left Heat Regulating Valve (N175) and Right Heat Regulating Valve (N176) are closed coolant hoses or coolant pipes to heater cores of heating system cool down.

• If one of these test requirements is not fulfilled, check the DTC memory for the Climatronic Control Module (J255) front A/C control head, perform output diagnostic test mode and read the measured value block. vehicle diagnosis testing and information system VAS 5051 in the "Guided Fault Finding" function.