Have your air conditioner inspected and serviced by a qualified HVAC technician. While it may seem your system is fine or that it was running efficiently when last used an HVAC technician can do a full inspection and cleaning of the system to insure it is running at peak efficiency. He can also correct minor issues before they become costly repairs. Think of it like this, you wouldn’t drive your car all year without checking the tire pressure or changing the oil. Your air conditioner is an expensive system, it deserves regular maintenance.