Test Requirements
- Pay attention to the general information for checking the refrigerant circuit pressure. Refer to GENERAL INFORMATION FOR CHECKING THE REFRIGERANT CIRCUIT PRESSURE .
All of the test requirements marked with a "*" are vehicle-specific and described in the repair information for the vehicle. Refer to COOLING OUTPUT, CHECKING .
General test requirements (these only have an influence on the pressure gauge display for this measurement with the A/C system switched on)
- Radiator and condenser are clean (clean if necessary) *.
- The thermal insulation at expansion valve is OK and properly installed.*
- Ribbed belt is OK and properly tensioned. Ribbed belt for A/C compressor and generator are OK and correctly tensioned.*
- The drive unit for the A/C compressor is OK and installed correctly. *
- All air ducts, covers and seals are OK and properly installed *.
- The A/C system diagnostic does not detect any malfunctions (when the engine is running and the A/C system is switched on), and no compressor shut-off condition is displayed in the measured values (only for vehicles with "A/C system" diagnostic). Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function for the A/C system.
- Air flow through dust and pollen filter not obstructed by dirt *.
- All instrument panel vents are open *.
The A/C compressor is driven by different components depending on the engine (belt or input shaft). To protect these components and the engine an overload protection in installed in the belt pulley or the A/C compressor drive unit which disengages by a difficult to move A/C compressor. Refer to COOLING OUTPUT, CHECKING (vehicle-specific repair information) and A/C COMPRESSOR .
On specific versions the fan is switched on after the refrigerant circuit pressure specified value is exceeded. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function of the A/C system.
Additional test requirements (these have an influence on the display of the pressure gauge on this measurement)
- Vehicle is not exposed to direct sunlight. Refer to COOLING OUTPUT, CHECKING .
- The ambient temperature is greater than 15 °C (59 °F).
- The ignition is switched off.
- The A/C service station in connected to the refrigerant circuit. Refer to A/C SERVICE STATION ON REFRIGERANT CIRCUIT, CONNECTING .