I have a Bentley repair manual for my D2 A8L 2001 and there is no "coolant exchange valve" that my dealer claims is broken and the source of the whining fan noise when my A/C is on. The noise is even louder outside the car on the driver's side just below the windshield. Does anyone know what could possibly be the source of this fan noise? Goes away when the A/C is shut off. I know the A/C fan is in the middle of the engine bay below the windshield. Any help would be great. Thank you in advance!

Richard
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