Within the first four years of a cars's life, there's no need for maintainance. After that, Experts recommend an inspection of the air conditioning systems every two years, in order to check the loss of refrigerant. If this cannot be compensated, the MAC system has to take a higher load and can be broken more easily. Not switching on the air conditioning system at all is not advisable as well: The refrigerant does not pass through the circulation anymore and thus it can't grease the components and moveable parts optimally.
Ask for information: When buying a new car, ask for the refrigerant filled in the MAC system and the additional fuel consumption due to the use of the air conditioning. Depending on the type of the MAC system, the fuel consumption of your car may increase up to two liters per 100 kilometers.