The exhaust volume of a fixed displacement compressor increases proportionally with the increase in engine speed. It cannot automatically change the power output according to the demand for refrigeration, and has a greater impact on the engine's fuel consumption. Its control is generally achieved by collecting the temperature signal of the evaporator outlet. A variable displacement compressor can automatically adjust the power output according to the set temperature. The air conditioning control system does not collect the temperature signal of the evaporator outlet, but controls the compression ratio of the compressor according to the pressure change signal in the air conditioning pipeline to automatically adjust the outlet temperature.

Crankshaft connecting rod compressor. During the operation of this compressor, the piston is driven to reciprocate by the connecting rod, and the working volume composed of the inner wall of the cylinder, the cylinder head and the top surface of the piston will change periodically, thereby playing the role of compressing and transporting the refrigerant in the refrigeration system. Axial piston compressors can be called the second generation compressors. Common ones are rocker plate or inclined plate compressors, which are the mainstream products in automotive air conditioning compressors.

The cylinder shape of the rotary vane compressor is round and elliptical. In a circular cylinder, the main axis of the rotor has an eccentric distance from the center of the cylinder, so that the rotor fits tightly between the suction and exhaust holes on the inner surface of the cylinder. In an elliptical cylinder, the main axis of the rotor coincides with the center of the ellipse.

Scroll compressor, this type of compressor can be called the fourth generation compressor. The scroll compressor structure is mainly divided into two types: dynamic and static type and double revolution type. At present, the dynamic and static type is the most commonly used, and its working parts are mainly composed of a dynamic turbine and a static turbine.