BMW 7 Series: A/C Performance Test (R 134a)

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

1. Provision of a diagnosis system. Safeguard electrical system integrity by checking the fault memory (no faults in the fault memory).

2. Provide a thermometer with separate gauge.

3. Perform the test in a suitable workshop area with an ambient temperature between 20ºC and 30ºC.

Re 1:

Connect diagnosis system to vehicle and display evaporator temperature.

Re 2:

Position a thermometer with a separate gauge approx. 5 cm below the roof liner at the height of the B-pillar.

Lay gauge outwards out of passenger compartment.

Re 3:

Heat passenger compartment:

• "A/C button" is not activated during the heating process
• Close all windows and doors.
• Set air recirculation function.
• 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 (28ºC)
• Maximum blower speed (adjust 9 pixels from 9 possible on front A/C control panel)
• Run engine at approx. 2000 RPM until operating temperature is reached, then idle speed.

Air-conditioning performance test

Turn on A/C compressor via "A/C button" at a vehicle interior temperature of 50ºC.

Vehicles with MAX-AC button ("MAX"):

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

Vehicles without MAX-AC button ("MAX"):

• Set maximum cooling power by means of following steps:
  • Temperature setting = 16ºC
  • Blower setting 9 pixels of 9 possible
  • Stratification maximum cold (4 blue bars)

Evaporator sensor temperature must be < or = 15ºC after 3-4; minutes at approx. 2000 RPM.

DRAW OFF A/C SYSTEM if this temperature is not reached. Measure amount of refrigerant drawn off.

If drawn-off quantity does not correspond to specified fill quantity, supplement refrigerant and repeat test. See AIR CONDITIONING SYSTEM, AMOUNT OF REFRIGERANT.

If capacity is correct, continue troubleshooting by pressure measurement.

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