Method and apparatus for controlling air-conditioning systems

In a forced air multiple zone air conditioning system having heating equipment for heating air supplied to the zones, cooling equipment for cooling air supplied to the zones and air damper units for controlling air flow to the zones via the heating and cooling equipment, a control system comprising:

• (a) zone temperature condition sensing means for producing a zone condition signal;
• (b) command function generator means for producing a variable value command signal in response to varying zone condition signals;
• (c) controller means for governing operation of said heating and cooling equipment in response to the command signal, said controller means operating said heating equipment during a first command signal value range and operating said cooling equipment during a second command signal value range;
• (d) said damper units connected to said command function generator for altering air flow in said air conditioning system in response to command signal value changes in a third value range between said first and second value ranges, said damper units effective to alter air flow compatibly with operation of said heating equipment as the command signal values approach said first range of values and effective to alter air flow compatibly with operation of said heating equipment as the command signal values approach said second range of values;
• (e) said command function generator means comprising a command signal generator and a command signal modifier, said command signal modifier rendered effective at a command signal value between said first and second value ranges and coacting with said command signal generator to substantially prevent said command signal value from changing throughout a predetermined range of sensed zone temperatures.