Hi Pete, I had an x type 2.5 petrol with an 05 plate prior to my s type, and the aircon is up posed to be left on all the time. Whatever the temperature setting it always seemed to blow hot for a minute then set about getting to the temperature required. My s type does the same. I think that a good run, as you suggest, would be the best course of action, and if it is a hot day, set the aircon fairly low, say 18 degrees centigrade. When [and if] that temperature is achieved, try setting at a higher temperature, say 25 degrees Centigrade. As you say, if it just runs lukewarm a regas should cure the problem. Let us know how you get on. Regards, Peter.