It is good to service residential air conditioner around 3 to 4 times per year and every month for office and commercial units.However, this period will diffes according to the amount of usage.
Air-conditioning service is essential for the efficient use of your air-con and therefore when you do not opt for any air-conditioning service the additional expenses is rather huge when there is a breakdown of the system. That would also affect the life span and performance of your air-conditioning system.
The coolness decreases with the continual usage of an air-con for many months and years at a stretch. Your air-con may also have water leakage issues because of choke up in the drainage system which will lead to more consumption of electricity in the future. Your air-con will also have frequent mechanical faults that will increase your air-con repair expenditure. A regular air-conditioning service is thus highly recommended.