Expansion Valve Function: Types, How It Works and Its Components

The expansion valve is one of the components of a car's AC system. Although many people are familiar with this component, not many understand the function of the expansion valve. Below, the functions, types, and workings of the expansion valve will be explained in detail. Check out the full review below!

Function of the Expansion Valve

In general, the function of the expansion valve is to channel freon in the car's AC, which will later be released through the evaporator. However, there are other functions that this component has.Here are some functions of the expansion valve component, among others:

1. Responsible for cooling the temperature of the refrigerant or freon. The expansion valve can lower the temperature to -30 degrees.
2. Responsible for the amount of freon channeled to the evaporator. The amount of freon channeled depends on the condition of the heat sensor in the sensing tube. The hotter the sensor part, the more freon is channeled.
3. Responsible for lowering the pressure of the freon. This is because the expansion valve helps the process of vaporizing the freon coming from the compressor. The purpose of vaporizing the freon is so that the evaporator can produce cold air more effectively. 

Read Also: Negative Impact of Too Much Freon in Car AC

Types and Working of the Expansion Valve

Until now, the expansion valve is divided into 3 types, here are the types along with their workings:

1. Temperature Control Expansion Valve

This type of expansion valve works using an orifice to regulate the freon that is channeled.

The freon will be channeled to the evaporator through the expansion valve. In this type of expansion, the amount of freon flowing is always according to the size of the orifice.

2. Capillary Tube Type Expansion Valve

This type has a heat sensing tube that functions to measure the temperature of the freon released from the evaporator. Here is how the capillary tube type expansion valve works:

• Freon or refrigerant will flow from the receiver dryer to the expansion valve. This occurs due to pressure from the compressor. However, the freon is not channeled to the evaporator first because the valve is still closed.
• Next, the freon that comes out of the evaporator generates hot temperatures. This temperature will later be detected by the heat sensing tube.
• The hot temperature detected by the heat sensing tube will be transmitted to the valve membrane through the capillary tube. The condition of the membrane in the expansion valve will continue to bend according to the height of the hot temperature.
• This bending causes resistance of the needle (ball) against the spring.
• The continuously pushed needle will cause the expansion valve to open.

3. Box Type Expansion Valve

This type is widely used in the latest vehicles today. The box type expansion valve works using pressure and temperature sensors to regulate the amount of freon. Subsequently, the freon will be channeled to the evaporator through the expansion valve. 

Components in the Expansion Valve

Inside the expansion valve, there are the following components:

1. Inlet Channel: Functions as the entrance for freon from the dryer.
2. Outlet Channel: Functions as the exit for freon from the expansion valve to the evaporator.
3. Membrane: Functions to transmit the heat detected by the heat sensing tube, to create resistance between the needle and the spring. This resistance will open the expansion valve.
4. Pressure Spring: Functions to return the membrane position so that the valve closes perfectly when the expansion valve does not work properly.
5. Needle: Functions to resist the spring to keep the valve open.
6. Body: Functions as the housing of the expansion valve.
7. Heat Sensing Tube: Functions as the heat sensor for freon.
8. Capillary Tube: Functions to transmit the heat from the heat sensing tube, which is then channeled to the membrane.

Thus, the review regarding the function of the expansion valve, along with its types and workings. Make sure you always pay attention to the condition of the expansion valve, so that your car's AC does not have problems. If left unchecked, the cabin condition will feel hot.