With the above vehicles annoying, whistling or/and humming noises may be heard from the vehicle rear end. This only affects vehicles with a second evaporator (rear evaporator). The noise is especially noticeable when the idle speed is slightly increased.
Proceed as follows to rectify the problem:
If the above measures do not lead to the desired results, it is possible that the expansion valve is the cause of the noise. To access the expansion valve, only the right-hand paneling on vehicle rear end needs to be released and carefully folded back. The fixing nut of the expansion valve should be tightened to a torque of 23 Nm.
Important safety note
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