You don't need to do anything special to it. The only advice is to use it regularly, even in the winter. Many people think that air conditioning (or climate control) is just for cold air, but it's even more useful in the winter when it comes to clearing steamed up windscreens. So regularly using it is a must. The systems are usually very reliable and it will be checked during your routine annual service. Older system can sometimes need re-gassing but this is a fairly cheap thing to get done.