There was a recent thread where the vehicle was pre-facelift and it still it had the facelift wiring for aux fan. So the supply comes from 60 A main fuse (F107) behind front fuse box.

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E39 530dA -02 M-Sport Messing metallic
E53 X5 3.0dA -06 Sport Stratus grey
E70 X5 40d -12 M-Sport Space grey