BMW X3 Service & Repair Manual: A/c performance test

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

1. Connect diagnosis 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 18º C.

4. Vehicle temperature should be approximately the same as the ambient temperature in the workshop.

5. Engine must be at operating temperature (does not apply for electric vehicles).

Heat passenger compartment:

• "A/C button" is not activated during the heating process
• Close all windows and doors.
• Set air recirculation function.
• Select air distribution mode for footwell and defrosting.
• On vehicles with CID: In A/C menu (CID) in Air distribution index tab: 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 ºC (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 minimum temperature
  • 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 minutes measure both ventilation temperatures with a thermometer at the same time (fresh air grille center, left and right). The measured temperature must be ≤ 16 ºC and the difference between right and left may not be greater than 2 ºC.

If one or both temperature specifications is not reached DRAIN OFF HEATING AND AIR CONDITIONING SYSTEM. Measure amount of refrigerant drawn off.

If drawn-off quantity does not correspond to SPECIFIED FILL QUANTITY : supplement refrigerant and repeat test.

If capacity is correct, continue troubleshooting by pressure measurement.