Energy efficient control method for a manually regulated vehicle heating and air conditioning system

An improved method of operation for a vehicle heating and air conditioning system (10) electrically positions a temperature control actuator (56) in accordance with a first temperature control schedule (138) for coordinated control of compressor capacity and heating of the discharge air when air conditioning is enabled, in accordance with a second temperature control schedule (122) when air conditioning is disabled. Both first and second temperature control schedules position the temperature control actuator (56) as a function of the setting of the driver-manipulated temperature selector (100). The first control schedule positions the temperature control actuator (56) to provide a linear relationship between the temperature selector setting and the air discharge temperature during coordinated control of the compressor capacity and the temperature control actuator (56) when air conditioning is enabled, and the second control schedule positions the temperature control actuator (56) to provide a linear relationship between the temperature selector setting and the air discharge temperature when air conditioning is disabled.