Test Requirements

Test Requirements

Special tools, testers and auxiliary items required

• Vehicle diagnosis, testing and information system (VAS5051B) (or Vehicle Diagnosis and Service System (VAS 5052) ).

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

• Ambient temperature greater than 15 °C.

• Clean radiator and condenser (clean if necessary).

• The ribbed belt, which drives the A/C compressor, is OK and is tensioned correctly. The ribbed belt is actually driving the A/C compressor.

• All air guides, covers and seal OK and properly installed.

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

• Air intake apparatus (in fresh air and recirculating air mode) is not impaired by soiling or components installed as retrofit.

• Vehicle not exposed to sunlight.

• Engine is warm.

• The A/C control module (J301) DTC memory was checked and erased, basic setting was performed using Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding" function.

Adjustments on vehicle

• Open all instrument panel vents.

• Close hood.

• Set the lowest possible temperature (temperature rotary switch turned all the way to "cold") on A/C control module (J301).

• Switch on the A/C compressor using the AC button on A/C control module ( the indicator lamp in the AC comes on)

• Switch A/C system to recirculating air mode by pressing "recirculating air mode" button on A/C Control Module (indicator lamp in "recirculating air button" lights up).

• Set the air flow direction to "instrument panel vents" via the air distribution rotary switch on A/C Control Module.

• Set speed 4 on fresh air blower rotary switch.

Functions with engine running

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

• A/C system initiates recirculating air mode, the fresh air intake is closed and the recirculating air intake is opened (Fresh Air Blower extracts air from passenger compartment under instrument panel / glove compartment).

• The Coolant fans (V7) run (activation and speed depends on pressure in refrigerant circuit and on the engine temperature).

• Depending on version of A/C control module (J301) , coolant fan (V7) is switched on immediately or only from a certain pressure in refrigerant circuit (from a pressure of 9 bar at this time). The coolant fan activation is displayed in the measured values block using Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding" function.

• If one of these test requirements is not fulfilled, check the DTC memory, perform a final control diagnosis and read the measured values block using Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding" function.