What is the fundamental difference between automatic air conditioning and semi-automatic air conditioning?

The most fundamental difference between automatic air conditioning and semi-automatic air conditioning is:

(1) Air conditioning system is a comfort device, and the temperature inside the car is an important indicator of comfort. The inside temperature depends on the outside temperature, air flow and solar radiation. When the temperature outside the car exceeds 20 degrees Celsius, the comfortable temperature inside the car can only be achieved by cooling with cold air.

(2) Traditional air conditioners are manually controlled. There is a temperature adjustment knob on the air conditioning control panel, which is actually a variable resistance device. It forms a series circuit with the temperature-sensing resistor in the evaporator. When the temperature changes, the resistance of this circuit changes, thus controlling the electromagnetic clutch of the compressor. When the temperature is low, the clutch is disengaged and the air conditioner stops working. When the temperature is high, the clutch is closed and the air conditioner continues to work. This control method is simple, but the temperature control adjustment is rough.

(3) The automatic air conditioner is self-adjusting, which can automatically adjust the air outlet temperature according to the temperature of the carriage, with stable and flexible performance and fine temperature control and adjustment. In addition, the automatic air conditioner has a self-checking device, which can find hidden dangers early.

Automatic air conditioning should also have a "control center", plus testing instruments and other components:

(1) The automatic air conditioning control system consists of four parts: one is the sensor part, which is responsible for temperature information feedback. The second is the "control center" of the system, which is the ECU of the air conditioning control unit. Thirdly, the control part, including condenser motor and evaporator motor of air conditioning system, including mixed airflow motor and airflow motor, is used to control the combination of cold and warm air and open or close the air outlets on the front, sides and feet. The fourth is the self-inspection and alarm part. From the above structure alone, the automatic air conditioning of modern cars is much more complicated than the traditional air conditioning.

(2) The sensors of automatic air conditioning control system generally include interior temperature sensor, exterior temperature sensor, evaporator temperature sensor, solar energy sensor and water temperature sensor. Among them, the water temperature sensor is located at the water outlet of the engine and feeds back the temperature of cooling water to the ECU. When the water temperature is too high, ECU can disconnect the compressor clutch to protect the engine, and at the same time, ECU controls the valve of cooling water to the heating core according to the water temperature.

(3) Each sensor feeds back the temperature information to ECU, and ECU controls the temperature of airflow through the proportion of cold and warm air in the "mixed wind stall". For example, when the temperature is too low, the ECU instructs cold air to flow through the heating core to raise the temperature, and when the temperature in the carriage reaches a predetermined value, the ECU will issue an instruction to stop the operation of the "mixed air stall" servo motor. At the same time, ECU also controls the air flow direction through the "mode wind gear" servo motor to determine the blowing angle of the air outlet.