Ok a more useful post this time, as Ben said chances are its a nackered heater matrix, they can seize shut which means that your blowers will blow but the matrix isn't feeding isn't hot water to heat up the air. I had this problem a lot on my old fiesta, it blew three matrix' until I fitted s bypass pipe for the summer and bought a ford ka matrix which solved the problem in the winter.
If it is seized be very careful, it might not be the case in the Clio but in the fiestas it would cause a backlog in hot water and stop it circulating around the cooling system causing the car to overheat! If the car is under warranty I would keep a close eye on the temperature gauge and get it too a dealers ASAP.