Using your air conditioning can cause you to have higher energy bills. Although there are ways to lower them; just make sure your AC unit is clean and up to factory specification, and make sure your vents and outdoor unit are clean including the coils.
They can get covered in dust or leaves or when it rains hard, they can be covered in mud. In Kansas, cottonwood can build up on the AC unit and coils. This restricts the airflow and causes overheating to happen easier, which in turn raises the electricity bill.