Air conditioning problem 2013 Audi A4

[Bobrun]

Hi, can anyone help me with a problem I have with my air conditioning, when I start a journey my air conditioning works perfectly and for as long as the journey lasts, no matter the time or distance. As soon as I stop and then restart the engine the air conditioning blows warm, if I keep switching the air conditioning on and off it will eventually restart, sometimes quite quickly and sometimes it takes a long time, when it does come back on it works perfectly. Any advice would be greatly appreciated.