How the Car AC System Works: A Complete & Easy-to-Understand Guide!

The way a car's AC system works involves a fascinating series of physical processes and several key components. Understanding this system not only broadens your knowledge but can also help you detect issues early or even perform basic maintenance.

In this article, we will provide a complete and easy-to-understand explanation of how a car AC system works, from its main components to its overall working principles. We will also give an overview of potential repair costs should any problems arise.

How the Car AC System Works

Understanding how a car AC system works is very important for vehicle owners, as it helps them maintain and operate this feature more effectively. The AC system in a car operates on the basic principle of a closed-loop cooling cycle that relies on heat transfer through the circulation of refrigerant (Freon).

This cooling process involves several key components working together in sync. Here is the complete explanation for you.

1. Compressor

The compressor is the heart of the car's AC system. Without the compressor, the entire process of cooling the air inside the cabin would not function. Its role is to pump refrigerant (Freon) in the form of low-pressure gas from the low-pressure side of the AC system and compress it into high-pressure, high-temperature gas.

This process begins when you activate the AC system via the control panel inside the cabin. When the AC button is turned on, the magnetic clutch on the compressor engages with a pulley driven by the car’s engine. This pulley rotation allows the compressor to start pumping Freon throughout the system.

Here is a simple breakdown of how the compressor works:

• The refrigerant in low-pressure, low-temperature gas form is drawn from the low-pressure side of the AC system.
• The compressor compresses this gas into a high-pressure, high-temperature state.
• The high-pressure Freon is then sent to the condenser for further cooling.

Additionally, the compressor’s operating speed typically corresponds to engine RPM. The higher the engine RPM, the faster the compressor pumps Freon.

2. Condenser

After the Freon is pumped and compressed by the compressor into a high-pressure, high-temperature gas, the next step in the AC system is heat dissipation in the condenser. The condenser functions as a heat exchanger. This component resembles a radiator and is typically located at the front of the vehicle, just behind the grille, to maximize airflow.

Here is how the condenser works:

• High-pressure hot gas Freon enters the condenser tubes.
• As the Freon flows through these tubes, the radiator fan or air from the moving vehicle helps cool the tubes and lower the Freon’s temperature.
• During this cooling process, heat from the Freon is released into the outside air via the cooling fins on the condenser.
• Once the Freon’s temperature drops significantly, it changes into high-pressure liquid form.

This phase change is known as condensation. At this stage, effective heat dissipation is crucial because it determines how efficiently the AC system can cool the cabin air.

If the condenser is dirty or clogged, the heat dissipation process becomes less effective, causing the Freon to be insufficiently cooled when it reaches the evaporator. As a result, the air coming from the cabin vents may not feel cool enough, even if the other components are working properly.

3. Receiver/Drier

The receiver/drier is also one of the critical components in the AC system, particularly in Thermal Expansion Valve (TXV) type systems. Its main functions are to filter and temporarily store liquid Freon before it enters the expansion valve.

After the Freon changes to high-pressure liquid form in the condenser, it is not yet completely clean. This is where the receiver/drier plays a crucial role:

• It filters out solid contaminants such as metal shavings or residual lubricants that could damage components like the expansion valve and evaporator.
• It removes water vapor or moisture that may have entered the Freon stream. If not properly filtered, this moisture can freeze when the Freon pressure and temperature drop, potentially clogging the system and damaging AC components.

The receiver/drier contains desiccant (a moisture-absorbing substance), which absorbs water molecules from the liquid Freon. If the desiccant becomes saturated or damaged, its filtering effectiveness decreases, raising the risk of AC system damage.

4. Expansion Valve

After the high-pressure liquid Freon passes through the receiver/drier, it must undergo a pressure change to effectively absorb heat in the evaporator. This is where the expansion valve plays a vital role.

This component regulates the flow of Freon into the evaporator by drastically reducing its pressure. This pressure reduction transforms the high-pressure liquid Freon into a mixture of low-pressure liquid and gas with a much colder temperature.

5. Evaporator

After passing through the expansion valve, the mixture of low-pressure liquid and gas Freon now flows to the evaporator. This is where the core process of the AC system takes place: absorbing heat from the cabin air.

The evaporator is shaped like a small radiator located inside the cabin, usually hidden behind the dashboard or blower. It is made of heat-conductive materials like aluminum, with many fins to maximize surface area for heat absorption.

Here is how the evaporator works:

• Air from inside the cabin is drawn in and directed to the evaporator via the AC blower.
• As the warm air passes over the evaporator’s surface, heat from the air is absorbed by the Freon circulating through the evaporator tubes.
• This process increases the Freon’s temperature and causes it to fully evaporate, while the air, having lost its heat, becomes cool and is circulated back into the cabin.
  The Freon that has absorbed heat returns to the compressor in low-pressure gas form to begin the cooling cycle again.

6. Blower

After the air is cooled by the evaporator, the next task falls to the blower, a vital component in the AC system. Without the blower, the cool air generated by the evaporator would never reach the cabin.

The blower in a car AC system functions by pushing or blowing cold air from the evaporator through the air ducts (AC vents) into the entire cabin. The blower acts as the driver of airflow, ensuring cool air is evenly distributed throughout the cabin.

Thus, the blower is responsible for pushing cooled air into the cabin after it is processed by the evaporator. If the blower malfunctions, cool air may not be properly distributed, even if the rest of the AC components are working normally. This is why the blower is a crucial part of the AC system in maintaining passenger comfort inside the cabin.

Source: rustpro.id

Summary: How the Car AC System Works

In general, a car AC system operates on the same principle as a room air conditioner. It works by converting the refrigerant (Freon) from liquid to gas through a cycle of circulation and pressure changes, absorbing heat from the cabin and releasing it outside the vehicle. This process keeps the cabin air cool and comfortable.

Here is a summary of the workflow:

1. You turn on the car’s AC.
2. The compressor begins pumping Freon and raising its pressure.
3. Hot gas is directed to the condenser to be cooled.
4. Liquid Freon enters the receiver/drier for filtering.
5. Freon pressure is reduced at the expansion valve.
6. Cold Freon enters the evaporator, absorbing heat from the cabin air.
7. The car’s AC blower pushes cool air into the cabin.

Estimated Car AC Repair Costs

Car AC repair costs vary greatly depending on the type of damage and the components that need to be replaced. Here is a general estimate:

• Freon refill: IDR 150,000 – IDR 300,000
• Blower replacement: IDR 300,000 – IDR 700,000
• Compressor service: IDR 500,000 – IDR 1,200,000
• Evaporator/condenser replacement: IDR 800,000 – IDR 1,500,000

To avoid unexpected expenses, it is advisable to perform regular maintenance, such as cleaning the cabin filter and checking freon pressure.

That concludes our explanation of how a car AC system works. We hope this information is helpful and gives you a better understanding of your vehicle’s cabin cooling system.

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