A/C performance test

Observe the following conditions prior to the A/C performance test: 

1. Connect diagnostic system. Check of the fault memory (no faults in the fault memory).
2. Attach a thermometer with separate display element to the head restraint. Lay display element outwards out of passenger compartment.
3. Perform the test in a suitable workshop area with an ambient temperature above 18° C.
4. Vehicle temperature should be approximately the same as the ambient temperature in the workshop.
5. Engine must be operating temperature (does not apply for electric vehicles).
6. ECO PRO mode must not be switched on.

Heat passenger compartment: 

• "A/C button" is not  activated during the heating process
• Close all side windows and doors
• Set recirculated-air mode.
• Select air distribution mode for footwell and defrosting.
• On vehicles with CID:  In A/C menu (CID) in air distribution index: select 100 % footwell for driver and front passenger and 100 % defrosting for driver (this applies here to driver and front passenger)
• Maximum temperature setting
• Maximum blower speed
• Start engine (does not apply for electric vehicles)

Cool down passenger compartment: 

Switch on air conditioning compressor with "A/C button" at a vehicle interior temperature of 45°C (measured at the head restraint).

On vehicles with MAX-AC button: 

• Activation of MAX-AC (= maximum cooling power)

On vehicles without MAX-AC button: 

• Set maximum cooling power by means of following steps:
  • Setting low temperature value
  • Blower setting maximum
  • Stratification maximum cold (4 blue bars)
  • Only ventilation open
  • Close remaining flaps (air outlet only  from center fresh air grille, left and right)

After 5 min, measure both ventilation temperatures with a thermometer at the same time (center, left and right fresh air grille). The measured temperature must be < 16°C and the difference between right and left may not be greater than 2°C.

If one or both temperature specifications is not reached drain off heating and air conditioning system. Refer to SUCTION, EVACUATING AND FILLING HEATING AND AIR CONDITIONING SYSTEM (R134A) .

Measure the amount of refrigerant drawn off and compare with the nominal fill amount. Refer to SUCTION, EVACUATING AND FILLING HEATING AND AIR CONDITIONING SYSTEM (R134A) .

Check whether refrigerant loss is present:

• If there is a permissible loss of refrigerant, fill the refrigerant circuit with the nominal fill amount. Refer to SUCTION, EVACUATING AND FILLING HEATING AND AIR CONDITIONING SYSTEM (R134A) .
• If there is an IMPERMISSIBLE LOSS OF REFRIGERANT , check the refrigerant circuit for LEAK-TIGHTNESS . After rectifying the leak, fill the refrigerant circuit with the nominal fill amount. Refer to SUCTION, EVACUATING AND FILLING HEATING AND AIR CONDITIONING SYSTEM (R134A) .
• If there is no refrigerant loss, continue troubleshooting using the pressure measurement (only possible for vehicles with unregulated air conditioning compressor up to series E46/E53).