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How Car Air Conditioning Systems Work: A deep dive into functionality and components

CEO Khai Intela
Have you ever wondered how your car's air conditioning system actually works? Sure, we all want it to function flawlessly, but understanding the inner workings can enhance our appreciation for this modern convenience. In this...

Have you ever wondered how your car's air conditioning system actually works? Sure, we all want it to function flawlessly, but understanding the inner workings can enhance our appreciation for this modern convenience. In this article, we'll explore the theory, components, and operation of car air conditioning systems, shedding light on the magic behind the cool breeze on a scorching day.

Manipulating Refrigerant: The Key to Coolness

The fundamental principle behind car air conditioning systems lies in the manipulation of refrigerant, which transitions between a liquid and a gaseous state. As this transition occurs, heat and humidity are absorbed from the vehicle, allowing the system to emit cool and dry air.

To control this refrigerant transformation, the air conditioning system carefully manages both pressure and temperature.

Evolution of Refrigerants: From Harmful to Environmentally Friendly

In the past, automotive air conditioning systems relied on R-12, commonly known as Freon, as their refrigerant. However, scientists discovered in the late 1980s that R-12 was damaging the Earth's ozone layer, leading to a search for alternative options.

In the mid-1990s, manufacturers transitioned to a more environmentally friendly refrigerant called R-134a. This hydrofluorocarbon (HFC)-based refrigerant doesn't possess the ozone-depleting properties of its predecessor. Furthermore, there is a new refrigerant on the scene, R-1234yf, which produces fewer greenhouse gases and is already mandated in Europe.

Key Components: The Building Blocks of Car AC Systems

Let's delve into the essential components that make up automotive air conditioning systems:

1. Compressor

The compressor acts as the power unit of the system, separating the low-pressure side from the high-pressure side. It takes in low-pressure gas and compresses it into high-temperature/high-pressure gas. Located at the front of the engine and driven by a serpentine belt, the compressor is crucial for the system's proper functioning.

2. Condenser

The condenser plays a vital role in reducing the refrigerant's temperature while maintaining high pressure. It facilitates the transition of the refrigerant from a gaseous state to a liquid state. Similar to the engine radiator, the condenser uses forced air, either from a fan or vehicle movement, to transfer heat. You can find the condenser mounted in front of the vehicle, behind the grill.

3. Dryer

Equipped with a desiccant (a drying agent), the dryer's primary function is to remove water from the refrigerant. Additionally, it possesses some system-filtering properties. The dryer is typically positioned on the high-pressure side of the system, between the condenser and the metering device.

4. Metering Device

The metering device, whether it's an expansion valve or a fixed orifice tube, serves to lower the refrigerant's pressure. This rapid drop in pressure causes a corresponding decrease in temperature. Even after leaving the metering device, the refrigerant remains in a liquid state. The metering device is located on the high-pressure side of the system, between the dryer and the firewall.

5. Evaporator

The evaporator is where the refrigerant transitions back to a gaseous state, resulting in a cooling effect. The cabin air is cooled and dried as it blows across the evaporator. The evaporator is the only component mounted inside the passenger compartment, hidden behind the dashboard.

Understanding the path and characteristics of the refrigerant is essential:

  1. Low-temperature/low-pressure refrigerant enters the compressor as a gas.
  2. High-temperature/high-pressure refrigerant exits the compressor.
  3. The refrigerant cools and converts to a liquid state in the condenser while remaining under high pressure.
  4. The receiver/dryer removes water from the refrigerant, and the expansion valve reduces its pressure.
  5. Finally, the refrigerant converts back to a gaseous state in the evaporator, absorbing heat and leaving the air cool and dry upon contact.

To visualize the entire system, refer to the AC system diagram below:

ac system diagram AC system diagram

Ensuring Optimal Performance: Addressing Common AC System Failures

Given the high-pressure nature of automotive air conditioning systems, it's crucial to maintain a sealed environment. Failures can occur when refrigerant escapes or contaminants infiltrate the system.

If a component has a leak, simply recharging the system with new refrigerant will provide only a temporary fix at best. Identifying the leak, replacing the faulty component, and subsequently evacuating and recharging the system are necessary steps for a long-term solution.

A system leak not only impairs the AC system's cooling abilities but can also damage the compressor. Running with insufficient refrigerant, the compressor may overheat and harm itself. Since compressors are generally non-serviceable and costly to replace, prevention is key.

Moreover, the AC condenser requires a steady flow of air through its fins to function optimally. Road debris and dirt can obstruct airflow, leading to decreased system performance. Positioned directly behind the vehicle grill, the condenser is somewhat exposed and prone to partial blockage.

Your Career Outlook: The Need for Automotive AC Technicians

With almost every new car sold in the U.S. equipped with an air conditioning system, the demand for automotive AC technicians is on the rise. These professionals diagnose and repair AC systems regularly, both at dealerships and independent shops. Customers often complain about warm air, loud noises, or even water leaking inside their cars! As an automotive technician, specializing in AC systems can open up a host of rewarding opportunities.

Interested in pursuing a career as an automotive technician? Universal Technical Institute (UTI) offers comprehensive training programs where students learn about every vehicle system, including auto air conditioning. In less than a year, you can acquire the skills and knowledge needed to excel in this field. Visit our program page and request information to connect with an Admissions Representative today.

UTI and NASCAR Technical Institute Campuses Offering Automotive Technician Training

UTI and NASCAR Technical Institute have campuses across the United States, providing top-notch automotive technician training. Here is a list of our campuses:

  • Austin, Texas
  • Dallas/Fort Worth, Texas
  • Houston, Texas
  • Miramar, Florida
  • Orlando, Florida
  • Long Beach, California
  • Rancho Cucamonga, California
  • Sacramento, California
  • Avondale, Arizona
  • Bloomfield, New Jersey
  • Exton, Pennsylvania
  • Lisle, Illinois
  • Mooresville, North Carolina (UTI and NASCAR Technical Institute)