Windscreen Condensation

[irelandbuyer]

I've noticed recently that when the car (07 A8) is parked up that there's usually a lot of condensation on the interior windows. I've had my mechanic clean out the drains and they were pretty blocked all right and that sorted out any leaks coming from the sun roof. Still a good bit of condensation tho. So, if I open the windows and clear that off...I'm usually OK...

However, when i'm driving 1st thing in the morning and if I turn on the A/C to windscreen it totally fogs up, like in an instant. I had to pull over the other morning as I literally couldn't see out. It was like that for say 3-4 minutes until the car heated up and then it cleared. But it happens now most times when I turn it on. It's as if there's water trapped somewhere in the A/C system...

I can resort to perhaps dehumidifyer crystals but just wondering if there's something else I should be looking at? Any ideas lads?