Keeping the air conditioner maintained will not only prolong the life of the unit but significantly reduce energy costs. Call an HVAC professional to the house once a year. They have special equipment to test the pressure in the refrigerant lines to detect leaks. During this visit they will also clean both the condenser (outside part) and evaporator (inside part). This part of the task is actually very doable for DIY type homeowners. It is still good to call in the professional, but there is no reason why you can’t do an extra cleaning midway through the summer.
Be sure to keep changing the air filters every 2-3 months so these efforts are not wasted. If you have pets or are in the middle of a dusty projects, change the filters as a part of monthly maintenance.