Edit ArticleHow to Buy an Air Conditioner There are many factors to consider when choosing an air conditioning unit. Air conditioners vary in price, energy efficiency and cooling capacity. Modern air conditioning units have many advanced features to compare before making a choice. The type of air conditioner that is right for your home also depends on your room size, window or wall opening, and installation requirements. Research how to buy an air conditioner to choose a unit that will save money and energy while keeping your space cool. Shop for an air conditioner in the cooler months. Decide between a window, portable or wall air conditioning unit. Measure the rooms to be cooled. Check the cooling capacity. Compare the Energy Efficiency Rating (EER) of air conditioners. Make sure the louvers of the air conditioner are motorized or adjustable. Get advice and feedback. Try out the air conditioning unit in the store. Find out how to install the unit.