BMW 1 series - Noise when air conditioning system switched on | HELLA

In the above vehicles, an incorrect quantity of refrigerant may lead to noise generation when the air conditioning system is on.

Humming and droning noises may be caused by insufficient/excess refrigerant in the air conditioning system.

If the steering wheel judders while driving at an engine speed of 900-1100 rpm (AC on), this is often also an indicator that the refrigerant quantity is incorrect.

In order to remedy this problem, the refrigerant should be sucked out and the system refilled with the quantity of refrigerant recommended by the manufacturer.