[SJP99]

Apologies for not posting much sooner - whine solved on 2015 XC60 a while back. After months of Volvo dealers saying Volvo was puzzled, my local parts manager produced from behind the counter, a Volvo length of a/c pipework which incorporated some sort of 'baffle'. Apologies - don't know exactly what the part was called. It had many many bends in it, presumably to fit around other engine components. It was an official Volvo part so clearly Volvo had been working on a fix despite the dealer not knowing this. It solved the issue - I had no more whine for the remaining time I had the car. By then I was in process of changing vehicle, but did run it for several months without whine.
(Now in 2018 XC60 with different engine - no whine issues)