How much does Air Conditioning cost per month in 2010? Average AC cost per month/year

Air conditioners are a real life saver in unbearably hot summer weather. Unfortunately, they can run up a serious power bill as well. A small window mounted AC unit costs about $65 per month with near constant use. A central air based air conditioning system may cost anywhere from $100 to $300 or more depending on house size, local cost of power, and certain other factors.