Manufacturers suggest booking your car in for an air conditioning service every 3-4 years. It is important to book a service regularly because it gives a full clean and inspection of the entire system. Inefficient air conditioning places greater strain on your car's engine, requiring more fuel to generate cool air. This makes it more expensive to keep your car running.
It is important to note that an air conditioning service is not included in routine car services but has to be booked separately.