Fuzzy logic control of a variable displacement compressor in a vehicle air conditioning system

A non-linear control method for an air conditioning system (10) utilizes fuzzy logic to regulate the activation a displacement control valve (17) for a variable displacement compressor (12) for maintaining a system parameter, such as the evaporator outlet pressure or temperature, at a desired value. The control inputs include the system parameter to be controlled and a refrigerant pressure that reflects changes in the compressor displacement.