I've just bought a 1999 E36 series 316 SE, which has a dual zone climate control system with digital display. The car does not have the original user manual, but I think I've worked out how to use the climate control system, which seems fairly intuative.

The system seems to work correctly, though is slow to respond to inputs. However, if I reduce the fan speed to minimum such that the display blanks and (I assume) turns off the system, there is a few seconds delay for the unit to respond by shutting down the fan, but then there is still some residual background fan noise that seems to be from the climate control system, or at least within the dashboard structure. So I can't fully quieten the system. It's a shame as the car is otherwise very quiet, but I can't get rid of this subdued fan noise.

Can anyone advise me if this is normal for this series, or if there is an issue with the climate control sytem or perhaps there is another likely source of this fan type noise and I am blaming the climate control when it is in fact something else.

Any advise appreciated.