Air conditioning apparatus for automobiles

Claim 1

An air conditioning apparatus for an automobile having a compartment, comprising: means forming an air flow path opening into said compartment and having an upstream end and a downstream end; an air cooling unit including a compressor and an evaporator with said evaporator located in the air path adjacent the upstream end of said air flow path for supplying cooled air; a heater located within said air flow path downstream from said evaporator for heating a portion of the cooled air from said air cooling unit; an air mixing damper in said air flow path located between said evaporator and said heater for selectively bypassing a portion of the cooled air from said evaporator over said heater and then introducing the mixture of the cooled air and bypassed heated air into the compartment of the automobile; first means for sensing the temperature outside the compartment of the automobile and second means for sensing the temperature inside the compartment; means forming a control device for controlling said air mixing damper based on temperatures sensed by said first and second means inside and outside of the compartment to keep the inside temperature of the compartment at a constant temperature; means for actuating said air mixing damper; a variable resistor connected operatively to said air mixing damper; and a temperature detector for detecting the temperature of said evaporator or the temperature of the cooled air supplied therefrom and having an electrical resistance, said means forming the control device being responsive to the voltage across said variable resistor and said temperature detector in series for controlling said compressor based on a signal proportional to the series resistance of said variable resistor and to the resistance of said temperature detector.