How does the air Conditioner in the car work?

How does the air Conditioner in the car work?

Below we examine the components in detail, explain their function and examine the vulnerabilities to which the components are subject.

The expansion valve

The expansion valve or the throttle valve can be likened to a weir. Due to the restricted flow cross-section, there is a consistently high pressure upstream of the valve, and the working fluid is usually fed into the expansion valve in a boiling state.

In the expansion valve itself, part of the refrigerant already evaporates, another part remains in the liquid state and is fed through a membrane into the evaporator, where it expands and the liquid part also changes its aggregate state to gaseous, whereby the heat is extracted from the ambient air.

This component is a precision device that always supplies the evaporator with the same amount of working fluid. If you experience any issue in the car, you can call for the fastest towing service near your area.

Consequences of a defective expansion valve

The expansion valve is sensitive to overheating or icing and leaks. If the filter dryer no longer functions properly, dirt can also block the expansion valve. The consequences are overpressure or under the pressure of the air conditioning system, resulting in poor performance of the air conditioning system or even a failure of the air conditioning system.

The evaporator

In the evaporator, the refrigerant supplied through the expansion valve expands and, due to the influx of heat from the evaporator ambient air, turns into a gaseous state and cools. In this way, the ambient air cools before it is admitted into the passenger compartment of the vehicle.

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This is guaranteed by the internal fan, which ensures an exchange of cold and hot air. The second task of the evaporator is to clean and dehumidify the ambient air, as the humidity of the cooled air and suspended particles are deposited on the evaporator.

Consequences of a defective evaporator

The evaporator is a robust component, provided the internal fan is working properly. If the internal fan stops running, the evaporator can freeze. The evaporator can also be the cause of a side effect that occurs regularly after the long winter rest period.

During this time, fungi and bacteria can develop due to the condensation water that the evaporator attracts. The result is a musty smell coming from the ventilation system. In this case, the air conditioning system must be cleaned urgently, as this can pose a health hazard.

The evaporator works with the help of the radiator, for this purpose the radiator of the car must be in perfect condition. If you need a car radiator repair you can visit your nearby workshop.

The coolant

The refrigerant is a so-called working fluid in the air conditioning system used for heat transmission, so it absorbs heat at “low temperature and low pressure and releases heat at higher temperature and pressure” (DIN EN 378 – 1 par. 3.7 .1), whereby the aggregate state of the working fluid always changes. Currently, the use of R1234yf refrigerant is mandatory for new cars across the EU.

Consequences of too low a coolant level or too old a coolant

The refrigerant itself is virtually risk-free as long as the filter is replaced regularly and you pay attention to the level of the refrigerant because if the level is too low the air conditioner will not work properly.

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A rule of thumb says that an intact air conditioning system loses about 15% of its refrigerant every year. It must therefore be refilled regularly. Refrigerants have attracted attention in recent years due to a dispute between the Daimler Group and the EU.

The European Union has removed R134a refrigerant from circulation because it has a harmful effect on the environment and obliges car manufacturers to use only R1234yf refrigerant in the future.


What does the air conditioning compressor do?

The compressor controls the air conditioning system and compresses the gaseous refrigerant.

What does the air conditioning condenser do?

The condenser cools the refrigerant, which can reach a temperature of up to 70 ° C when compressed by the air conditioning compressor.

What does the air conditioning dryer do?

The dryer filters dirt particles from the air conditioning system and extract the water from the coolant. This protects the system from corrosion and malfunctions.

What does the evaporator of the air conditioning system do?

In the evaporator, the refrigerant evaporates, cools and then cools the ambient air, which is then directed into the vehicle. The evaporator also cleans and dehumidifies the ambient air.

What does the coolant do?

The refrigerant is used for heat transfer. At low temperature and low pressure, it absorbs heat, at higher temperature and pressure it emits heat.

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Shankar is a tech blogger who occasionally enjoys penning historical fiction. With over a thousand articles written on tech, business, finance, marketing, mobile, social media, cloud storage, software, and general topics, he has been creating material for the past eight years.

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