Car air conditioning systems consist of air conditioning and heating. On this page, topics such as how the car air conditioning system works, air conditioning system parts and malfunctions are explained. Before talking about the malfunctions of the air conditioning system, it is necessary to tell how they work. The car air conditioning system, which we need especially in the summer months, is one of the indispensable systems for the comfort of the driver and passengers.
Vehicle air conditioners are systems that help us cool down in summer and protect us from the effects of heat. Today, air conditioning is used as a standard in every package and model of the cars produced. Auto air conditioning system works on the same principle as the system in refrigerators.
*Vehicle air conditioning systems are only one of the parts that make up the car, you can check the car parts and tasks page to look at other parts and systems.
What are Air Conditioning System Parts?
Car air conditioning system;
- Refrigerant: It is the fluid circulating in the system.
- Air Conditioner Compressor oil: It is a special oil used for lubricating the compressor.
- Compressor: It has the task of pressurizing the refrigerant.
- Condenser: It is called air conditioner radiator. It contributes to the fluidization of the fluid.
- Humidity trap filter: It takes the moisture that may occur in the refrigerant gas and ensures that it is sent dry.
- Expansion valve: It helps to cool the environment by passing the refrigerant from liquid state to gas state.
- Evaporator: It is the area where the cooling process is done.
- Air conditioning fan: Blows air into the vehicle.
- Sensors: They are used to help the operation of the air conditioning system and to monitor its condition.
consists of parts. It will be explained in detail below.
*To have information about car brands, you can check the page named which car brand belongs to which country.
I – What is Air Conditioning Gas and What Does It Do?
R134A gas is used in auto air conditioning systems. The amount of refrigerant gas is very important for the performance and operation of the air conditioning system. A large amount of it affects the performance of the air conditioner system as badly as a small amount. For this reason, it should be ensured that there is correct amount of air conditioner gas.
II -What is Air Conditioning Compressor Oil and What Does It Do?
A/C compressor oil is the liquid that lubricates the compressor while it is running. Special air conditioning oil should be used. PAG=Poly-Alkylene-Glucol synthetic oil is used in the use of R134a refrigerant. The air conditioner works by dissolving in the air conditioner oil. For this reason, it is necessary to look at the amount of oil while checking the air conditioner gas during air conditioner maintenance. In order to fully understand the level, it is necessary to look after a certain period of time after the air conditioner is turned off. Oil should be added if necessary.
III – What is a Compressor and What Does It Do?
It is a kind of pump that pressurizes the low-pressure refrigerant gas coming from the evaporator and sends it to the condenser, that is, to the air conditioner radiator. The engine must be running in order for the compressor to work, as it takes its drive from the engine. While the engine is running, the pulley of the compressor will rotate because it is connected to the compressor with a v-belt. But the compressor is not on. In order for the compressor to be on, you have to press the air conditioner button, that is, the AC button. When you press the air conditioner button, the compressor will be electrified and the pulley will not turn empty and the compressor will start to rotate. The compressor that starts to work pressurizes the refrigerant gas and sends it to the air conditioner radiator.
IV – What is a condenser and what does it do?
The pressurized refrigerant gas coming from the compressor enters the air conditioner radiator, in other words the condenser. Thanks to the air conditioner radiator fan, the refrigerant entering the condenser liquefies and leaves the condenser. The refrigerant still in a pressurized state will go to the expansion valve. The task of the air conditioner radiator is to condense and liquefy the refrigerant gas.
V – What is a Humidifier Filter and What Does It Do?
The refrigerant leaving the condenser passes through the moisture trap filter before going to the expansion valve. The task of the moisture trap filter is to take the moisture in the liquid air conditioner refrigerant coming from the condenser. There is a strainer and a desiccant inside the moisture trap filter. Here, water and dirt are separated from the cooling gas. The desiccant filter must be changed within certain periods. The reasons are mentioned in the section of air conditioner malfunctions.
VI -Expansion Valve and What Does It Do?
The expansion valve is a needle valve as a valve type. It opens and closes according to the temperature and provides the passage of the coolant. The refrigerant coming to the expansion valve will turn into a liquid and gas mixture as it passes through the expansion valve. The refrigerant liquid-gas mixture coming out of the expansion valve will enter the evaporator. In short, the expansion valve sends the high-pressure refrigerant to the evaporator, reducing its pressure and allowing it to pass into some gaseous state. In electric expansion valves, there is a temperature sensor at the outlet of the evaporator, the coolant that enters comes out as it heats up; The temperature sensor detects this amount of heating, sends a signal to the expansion valve and the expansion valve increases or decreases the amount of refrigerant passing through.
VII – What is an Evaporator and What Does It Do?
The incoming gas-liquid mixture at low pressure will become completely gaseous until the refrigerant enters and exits the evaporator. During the transition from this liquid to gas, it takes the temperature in the environment and leaves the evaporator. The evaporator is the part that plays the leading role for the cooling of the environment. It lowers the ambient temperature.
VIII – What is Air Conditioning Fan and What Does It Do?
The air conditioner fan is the part that allows fresh air to be blown into the vehicle. It blows the air taken from the atmosphere or inside the car into the car. This air to be blown passes through the evaporator grills and is cooled. The cooled air will also cool the interior of the vehicle.
The refrigerant gas in the evaporator, which cools the air blown by the air conditioner fan, will come back to the compressor inlet in low pressure and completely gaseous state, and the cycle will be completed. Then the compressor pressurizes the refrigerant gas again and sends it to the condenser. The cycle will continue in this way until you turn the air conditioner switch off. When you turn the air conditioner button off, the compressor electricity will be cut off and the pulley will start to spin. In other words, the pistons in the compressor will remain stationary.
Average temperature and pressure values of the refrigerant circulating in the air conditioning system
Compressor outlet pressure can be between 14 bar and 18 bar, the temperature rises to 65 degrees.
Compressor inlet pressure may be 1.0 bar and slightly higher. If the pressure is too low, the compressor will not work because it will be damaged.
Condenser inlet and outlet pressures will be the same as compressor outlet. There will only be a temperature drop between the inlet and outlet, and the refrigerant that enters in gaseous form will come out in liquid form.
In the expansion valve and evaporator, the pressure drops to 1.0 bar and the temperature drops below 0 degrees. This decrease can be up to -10.
What are Vehicle Air Conditioning System Faults? What Are The Solutions?
From time to time, the air conditioning system may not cool the car for many reasons. If you say that the air conditioning system is not cooling, you are experiencing one or more of the problems listed below.
Types of Failure
I – Insufficient or excessive amount of air conditioning gas
We mentioned above the importance of gas amount in the air conditioning system. It is undesirable to have more air conditioner gas as well as less. When the air conditioner gas is low in the system, the compressor will not be able to generate enough pressure and the gas circulating in the system will not be able to fully perform its cooling feature. In order for the air conditioning system to work with full performance, it must work close to the above pressure and temperature values. Too much or too little refrigerant will cause it to go far from these values and will reduce the performance of the system and even prevent it from working.
II – Clogging in the desiccant filter
We have explained the working principle and function of the desiccant filter above. A blockage in the moisture trap filter will slow down the passage of the coolant and cause the pressure in the system to drop. In such a case, when you hold the humidifier filter by hand, you can see that it is cold. If the desiccant filter is cold, it is clogged and needs to be replaced.
III – Compressor outlet pressure drop
In a situation such as a decrease in compressor condition, the performance of the system will decrease as the refrigerant gas will not be sufficiently pressurized. In such a case, the air conditioner compressor should be serviced or replaced. The compressor condition must be complete so that the air conditioner system can work well.
IV – Pollution in the air conditioner radiator, that is, in the condenser
The pollution to occur in the air conditioner radiator, that is, the condenser, will prevent the cooling of the refrigerant gas in it, thus preventing the system from working. In order for the system to work, the refrigerant gas entering the condenser must completely turn into liquid until the outlet. In order for the condenser to be able to do this condensation, it must be clean and there is no pollution layer between the air coming from the air conditioner radiator fan and the radiator.
V – Deterioration or wear of the expansion valve
The expansion valve, which is the backbone of the cooling system, needs to work well so that the whole system works well. The deterioration or wear of the expansion valve will prevent it from fulfilling its duty fully and will disrupt the pressure change balance. This will disrupt the operation of the air conditioning system.
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