Combined U.S. factory shipments of central air conditioners and air-source heat pumps for December totaled 330,698, a 16 percent drop compared with December 2006 totals, according to the AHRI.

The Air-Conditioning, Heating and Refrigeration Institute, formerly the Air-Conditioning and Refrigeration Institute, also reported that combined U.S. factory shipments totaled 6.4 million in 2007, down 9 percent from the previous year.

Heat pump shipments for December totaled 115,556, down 14 percent compared with December 2006 shipments. For the year, heat pump shipments totaled 1.9 million, down 10 percent from 2006.