Expansion valve is a part that serves to control the amount of coolant that enters the evaporator. When speaking about its construction, the expansion valve is a variable section throttle. This spare part is set up behind the drier’s filter on the evaporator inlet branch. Its main function is to reduce coolant pressure and temperature to such a limit that when passing through the evaporator evaporation and intensive heat exchange to be provided. As for the sensing hole, it lowers the pressure of the fluid entering the valve. That coolant that enters the drier filter is a liquid under high pressure.

When the coolant passes through expansion valve opening, it is sprayed. At the same time, the temperature and pressure of the substance decreases. This is necessary to facilitate the entire evaporation process of the coolant directly in the evaporator. To find out how the amount of the coolant that passes through the thermostatic expansion valve is regulated let us describe the process. In thermal contact with the evaporator exhaust pipe there is located temperature sensor.