Method and control system for controlling an automatic HVAC system to prevent the discharge of air within a predetermined temperature range

A control system for automatically controlling a heating, ventilation and air conditioning (HVAC) system of a vehicle which discharges a flow of air at a discharge temperature to a passenger cabin of the vehicle, the HVAC system including a variable speed blower, means for varying air temperature, ducting, actuators having control modes for controlling the direction of air flow and the ratio of fresh air to recirculated air and sensors for sensing temperature within the cabin, ambient temperature and a target set point temperature, the system comprising:

• means for determining the difference between temperature within the cabin and the set point temperature to obtain a difference signal;
• means for defining membership functions and fuzzy rules between the difference signal and the control positions of the actuators;
• and
• means for generating a set of control signals to control the control mode of the actuators to prevent the HVAC system for discharging a flow of air into the cabin having a predetermined range of temperatures defined by first and second predetermined temperatures, the means for generating the set of control signals being based on the difference signal the discharge temperature, the membership functions and the fuzzy rules wherein the HVAC system is prevented from discharging a flow of air having a temperature within the predetermined range of temperatures into the cabin by controlling the temperature of the discharged air to be below the first predetermined temperature as the temperature of the air increases and approaches the first predetermined temperature and to be above the second predetermined temperature as the temperature of the discharged air decreases and approaches the second predetermined temperature.