An air conditioning system with a variable sensible heat ratio. The system includes a servomechanism that monitors the sensible and latent heat in the air being conditioned and adjusts the operation of the system accordingly. A microprocessor calculates the respective rates of change in sensible and latent heat and adjusts the operation of the system so that the desired amount of sensible and latent heat is removed at the same time, thereby conserving energy. The system includes a variable speed supply air fan and a plurality of subcooling coils. Under a first set of conditions, the fan is slowed down and the subcooling of the refrigerant fluid is increased. Under a second set of conditions, the fan is sped up and the subcooling is decreased.