Air Con not working properly in the front vents

[M Kelly]

My 2014 A6 C7 saloon has a problem with air con, would welcome any ideas as to what it could be please? 

Basically, with the climate set to lowest setting on both sides, only the drivers side gets cold and to the required temperature. The passenger side is like a normal temperature (not hot or cold). Works ok when you want heat both sides, the problem is only when you want cold, passenger side doesn't get down to temp. 

Audi advice: "probably needs a re-gas" but i'm pretty sure it's not that. Any ideas welcome please? 

[cliffcoggin]

Possibly one or more of the flaps in the ducts are not working. It's a common problem that the garage should be able to diagnose.

[M Kelly]

Thank-you for your advice, it’s appreciated.