You might have to get your air con refilled.
A lot of independent companies will do it for you,but it can cost around £50 or so,(cheaper than Renault!).
I recently bought a Renault 2005 1.5 Dci Megane Estate,and I thought the air con wasn't working,until my son showed me how to set the controls!
It's fine now!
My other car did it all automatically,once you pressed the button!
Doug Sinnott, June 2009