if your car's fan clutch is original from the assembly line, it might never work even when hot, it bleeds out its silicone oil over time and fails to operate.

however.

it should roar when you cold start the engine in the morning, that roar happens because the silicone oil pools in one corner of the clutch effectively engaging it, it should go quiet after a few seconds - new one roars for a good 30 seconds when cold started.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)