Definitely Yes , If you want to reduce your maintenance cost & prevent the failure of your air conditioner then you need a ac service contract. Every air conditioning system needs quarterly service, If you get a an ac service contract then no need to remember your next upcoming service date. This would be handled by AC Company who is providing services to you.
Onetime service reduces the failure / breakdown in your air conditioners So this would automatically save your maintaining cost for your ac.
Also the additional benefit is if any parts fails during the service contract period , You will get the minimum cost of repairing for that because you are a existing Inhouse customer for the company, So the complaints would be handled within 48hrs maximum.