In general they run ac current but modern high efficiency units run the compressor or freon pump on DC current as they can litterly slow down the compressor to match the btu capacity required to run at the highest efficiency. read more
Most air conditioners have a nameplate on the unit that identifies the type of refrigerant it contains, plus other information like as safety certifications and electrical ratings. For a central air conditioner, the nameplate is usually on the outdoor unit. read more