Maintenance saves you money. Period.
It's very easy to ignore the air conditioner until it breaks. But your air conditioning system needs maintenance just like any other piece of equipment.
Not having your air conditioning system serviced annually is like driving your car without ever having the oil changed. You are only getting a fraction of the potential lifetime.
Above is a graph showing the repair/maintenance costs by year for a new air conditioning system with (green) and without (red) maintenance. The result is clear: if you want to save money in the long run, maintenance is an investment you can't overlook.
Experience shows that a new system can last up to 20 years if given proper maintenance each year, where a new system that gets no maintenance is unlikely to last more than 6 years.