Cooling fan control method for minimizing the power consumption of a vehicle air conditioning system

An improved control method for a vehicle air conditioning system (10) including a refrigerant compressor (12) and a condenser cooling fan (32) adjusts the power consumption of the condenser cooling fan (32) in a manner to minimize the combined power consumption of compressor (12) and the condenser cooling fan (32) while maintaining adequate cooling of the condensed refrigerant. When the air conditioning system (10) is operating at less than full capacity, the combined power consumption of the compressor (12) and the condenser cooling fan (32) is determined for each of a series of operating intervals (120, 128). The change in the combined power consumption from one operating interval to the next is computed to determine the effect of a prior cooling fan power adjustment (128), and the power level of the cooling fan (32) is incrementally adjusted in the same direction as the prior adjustment so long as the prior adjustment resulted in at least a specified reduction of the combined power consumption (130). Otherwise, the power level of the cooling fan (32) is incrementally adjusted in the opposite direction so that the control continually seeks the cooling fan power level that will minimize the combined power consumption of the compressor (12) and condenser cooling fan (32).