Just been out in my 2002 v8 FF and when I started off put the air con on to centre and side vents and had a good air flow from them. After about 20 mins driving I noticed the air flow was hardly noticeable and I had not changed any settings. after leaving the car while doing some shopping I returned and all normal again for about 20 mins then the same thing happened fan was still working at same speed but very little air flow from vents
Hope someone has an idea
Thanks

Sounds fairly normal - things tend to ease off once the system "thinks" the cabin temperature / air exchange is under control. But agree would prefer if they just kept blowing.

You can always turn up the fans with the centre knob - take control!  .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999