You can make a homemade air conditioner, but it will not be as effective as a store-bought unit. There are two main types of air conditioners: evaporative and refrigerant. Evaporative air conditioners use water to cool the air, while refrigerant units use a chemical compound. To make your own evaporative air conditioner, you will need a fan, a cooler or ice chest, and a water source. Fill the cooler with water and place it in front of the fan. The fan will blow across the water, cooling the air as it does so. You can also add ice to the water to help speed up the process. Refrigerant units are more complex, and require special chemicals that you may not be able to find at your local hardware store. If you decide to try making your own refrigerant unit, be sure to do plenty of research beforehand to avoid causing any damage to your home or yourself.