Don't set your thermostat at a colder setting than normal when you turn on your air conditioner. It will not cool your home any faster and could result in excessive cooling and, therefore, unnecessary expense.
Change the filters regularly. Dirty filters restrict air flow, reducing efficiency and worse case, can cause the evaporator to ice up. Disposable fiberglass filters should replaced. Electrostatic or electronic filters need to be washed regularly.
Set the fan speed on high except in very humid weather. When it's humid, set the fan speed on low. You'll get better cooling, and slower air movement through the cooling equipment allows it to remove more moisture from the air, resulting in greater comfort.
Clean obvious obstructions such as newspaper, leaves, etc. from around the exterior of the unit.
Consider using an interior fan in conjunction with your window air conditioner to spread the cooled air more effectively through your home without greatly increasing your power use.
Be sure the thermostat is set in the cooling mode. Just setting the dial below room temperature will not activate the air conditioning if it is set in the heat mode.
Don't place lamps or TV sets near your air-conditioning thermostat. The thermostat senses heat from these appliances, which can cause the air conditioner to run longer than necessary.
Insects love warm electrical components and air conditioners are full of them. If you want to keep insects out, experts say do not use insecticides, because the electrical components will not like them. One option is to get a special cover for your relay switch, but be aware that it has to be installed by an air conditioning technician. The cheapest (and easiest) way to keep them away is to use a flea collar. To install the flea collar, shut the power off to the air conditioner and simply placed the collar near the relay switch.
Plant trees or shrubs to shade air-conditioning units but not to block the airflow. A unit operating in the shade uses as much as 10% less electricity than the same one operating in the sun.
If you have central air conditioning, make sure the outdoor units have clearance for air flow. Cut back any plants that may have grown too close.