Most window air conditioners do require Freon in order for them to work properly. There is a type of Freon referred to as R-22 or HCFC-22, and it was most common in air conditioner window units prior to 2010.
If there is any doubt as to what type of refrigerant is being used in a window air conditioning unit, the nameplate on the unit should be checked. The type of refrigerant used in the unit should be prominently displayed. A homeowner should never try to purchase or replace Freon on their own, as a special license is required to even handle the refrigerant.