Have you heard the news? The cost of R22 is rising because of the decreasing supply, and will no longer be accessible for use at all by 2020.
If you have an air conditioning system installed earlier than 2010, it likely uses R22 refrigerant, which is what causes the air coming from your air conditioner to be cool and comfy. The U.S. Environmental Protection Agency began phasing out R22 refrigerant in recent years because it was compounding the depletion of the Earth's ozone layer.