MD Mondeo Climate Control Temperature Issue

[Paulg05]

Just noticed something strange the last couple of weeks on my 2015 Mondeo Climate Control.

When i get into the car on mid 20 DegC days both the Drivers and Passengers temperature is set 20 DegC but the air coming out of right hand centre vent is warmer than the left hand centre vent.
When the vehicle was new it never really struggled on hot days but it seems to recently. I try to compensate by turning the drivers side down but it never really gets that cold.
Could it be down on refrigerant ?