1. A ducted refrigeration unit comprising two parallel chambers having a common inlet duct and a common outlet duct, damper means for selectively channeling air through one or the other of said chambers from said inlet duct to said outlet duct, an evaporator coil in each of said chambers, each of said evaporator coils having a plurality of relatively closely spaced fins on one end thereof and a plurality of less closely spaced fins at the other end thereof, said closely spaced fins being on the downstream end of each of said evaporator coils, refrigeration apparatus for supplying a condensed liquid refrigerant and a noncondensed hot gas refrigerant, valve means for selectively and alternately controlling the supply of said liquid refrigerant and said hot gas refrigerant to said evaporators, and control means for said valve means and said damper means to selectively direct air from said inlet duct to a first one of said chambers while directing said liquid refrigerant to one of said evaporators in said first one of said chambers and hot gas refrigerant to the other of said evaporators in a second one of said chambers.