Further digging finds the thread below - where Clan and others state....
"The AQS will not be the cause but likely to be i wouldn't know about that , but his first problem with blowing too cold one side has nothing to do with the AQS just about all the cars fitted with them over 8 years old have the AQS failed fault code and contunue to work properly . The fault is probably a faulty driver's side air temperature flap motor"
Any thoughts on that chaps?
https://www.volvoforums.org.uk/showthread.php?t=246271