Over the last few months when I have been on long drives I have started noticing a cold draft after 30 minutes of so of driving.

After waving my arms around the cabin I have discovered that the air vents (both windscreen and foot well) on the passenger side of the car are blowing out cold air, while the ones on the drivers side are blowing out nice warm air.
The climate control has been set to 22C or 24C on both sides. I have tried twisting the temperature selectors up and down in case there was a poor connection, but this seems to make no difference.

Any ideas please?

Regards Rob

The car is 2010 Td4 GS I was a happy Freelander 1 owner for 10 years, now a happy Freelander 2 owner.