01 Megane makes whirring noise on start

[sfenner92]

Since I've bought the car just over a year ago it makes a strange whirring noise when I start it. It lasts for about 15 seconds and it's loud enough to draw attention from people when starting. Once it finishes, that is literally the end of it until I start it again. It's worth noting when I adjust the fan speed or heat it makes a different pitched noise. Just wondering if this is common and what I can do to solve it.

Thanks