Where AT=f (fan speed, evaporator coil, and box
temperature). Those of skill in the art Will be able to
approximate AT in light of the teaching of the present
invention, and Will further appreciate that that value Will
vary depending upon the components used in a particular
system. Based upon testing, assignee has determined that its
commercial embodiments of the present invention could
approximate AT as a constant of 3° C. In addition, applicants
have found that Whenever controller 150 exercises this
control mode, the desired superheat level can be set to a
constant.