Increasing demand toward driving comfort steers automobile engineers to spend more and more effort on refining the automobile air conditioning system. The system is of high order and operated at the presence of several disturbances. The control algorithm should be able to control the evaporator out temperature with the acceptable control action. In this work, the sliding mode control is adopted for its advantage of dealing with high order, nonlinear system. Besides, several linear and nonlinear observers are proposed such that the controller may be implemented under the constrain of limited sensor set.