User information

In order to facilitate selection of the correct menu entry, the following section describes which process is to be used during fault diagnosis.

1. Fault entry present 
   • Electric A/C compressor
   • Evaporator temperature sensor
   • Refrigerant pressure sensor

   If fault entries (DTCs) related to the above-listed components are present, it is essential to diagnose the sources of these malfunctions first. For this, observe the fault code descriptions and proceed by selecting "testing electric components" from the menu, then select the component for which the fault (DTC) has been entered from the next menu.

2. No fault code entered in fault code memory 

   If no fault entry is present for a malfunction related to the air conditioning system:

   1. Exit the test module and check the function structure in [!] "Current fault patterns" to determine whether a current fault pattern corresponding to the malfunction is present, and if so, work through the procedure for this fault pattern.
   2. Owing to the system's configuration, electrical malfunctions can occur that are not detected by the affected component's control unit (and thus not entered in the fault memory). E.g. an insulation defect on a line or coil. Electrical operation of components in which defects are suspected can be checked by selecting "Testing electric components" from the menu.
3. No fault (DTC) entry is present and no electrical fault has been diagnosed 

   The test module can be used to test the entire operational sequence, which equates with testing all of the components involved in executing the function under scrutiny. Proceed by selecting the correct malfunction (such as no or inadequate cooling) from the menu, then work through the specified procedure. Other potential malfunctions (such as noises, odors, temperature variations...) are listed in the menu under "Other malfunctions".

What test procedures can be accessed using the individual menu selections? 

• No or insufficient cooling power: 

  Comprehensive non-electrical test of the "refrigerant circuit" system.

• Check of electrical components 

  Functional check with electrical testing of the affected components.

  • Electric A/C compressor 
  • Evaporator temperature sensor 
  • Refrigerant pressure sensor 
• Other problems 

  Comprehensive non-electrical testing for other malfunctions and defects in the refrigerant circuit

  • Temperature differences at the front 

    Difference in air-discharge temperatures from the vent outlets on the driver's and passenger's sides although identical settings have been selected for both sides at the heating and air-conditioning system control panel.

  • Noise 

    Noises coming from the area around the heater and air conditioner, or the refrigerant circuit

  • Odors 

    Odors from the area around the heating and air-conditioning system.

  • Condensation/water ingress 

    Condensation on the windscreen.

• Leaks in the refrigerant circuit 

  When there is a suspicion of leakage in the refrigerant circuit this process checks the circuit for leaks.

• Display system values 

  Status display of the data relevant to the refrigerant circuit. The system data can be used to assess the condition of the refrigerant circuit, providing clues to possible malfunction sources.