Automobile Air Conditioning Systems

Automobile Air Conditioning Systems

The very first climate control systems for cars appeared before the Second World War. This option cost as much as one third of the car. In 1933 in the United States, these devices were already considered an integral part of living quarters. But it wasn't until 1936 that engineers began developing air cooling systems for various vehicles. The first air conditioning systems appeared in road trains for passengers. The principle of operation of an automobile air conditioner was the same as in refrigerators. It has not changed today. However, few people know what this system is.

The most important word in the concept of "car air conditioning system" is the word "system" itself. This means that it consists of several elements, and like most other systems, these components must work, and they must interact with each other. In this article, you will find out what parts are needed for the correct functioning of air conditioning. Thus, you can find out for yourself how the system works. In addition, the information provided contains practical advice for keeping each part of the air conditioning system in good order. In conclusion, you will be presented with data on how to understand that the air conditioner is faulty and how to eliminate the reason for the problem.

What are air conditioning parts?

What are air conditioning parts?

In modern passenger cars, the AC has both "manual" and automatic control (climate control). Regardless of how the AC is controlled, its structure is the same in the first and second cases.

The air conditioning system consists of such parts like:

  • a compressor that compressing refrigerant to a vapor state of high pressure and high temperature
  • a radiator (condenser), in which the refrigerant is cooled and turns into a liquid state
  • a receiver-drier, where the refrigerant is filtered, passing into an intermediate state (low-pressure liquid)
  • an evaporator, in which the liquid refrigerant is converted into vapor with the release of cold
  • pipelines representing the transport system for the refrigerant
  • the filling valve and pressure and temperature sensors are also part of the air conditioning system

Automatic air conditioning control differs from mechanical control by the presence of a processor that follows a preset program for the air temperature entering the car. Control over the temperature in the cabin is carried out through changes in the fan speed and angles of deflection of the dampers; in addition, when there is no such need, the automation can turn off the air conditioner compressor.

The air conditioner's operation is based on the property of freon to absorb heat during the transition from a liquid to a gaseous state and to release it during the reverse transformation. This is if you explain the process of the system briefly. In fact, air conditioning parts have a fairly large process, but it is not complicated in its understanding.


The compressor is one of the most important parts of the entire air conditioning system. By compressor, we mean the compressor itself, an electromagnetic clutch, and a drive pulley with a bearing. This part of the air conditioning system has two functions:

  • compresses the gaseous refrigerant from 1-3 bar to 12-20 bar
  • ensures circulation of freon through the system

It is a rather complex, accurate, and, as a result, expensive mechanism. The compressor is very "afraid" of dirt, liquid freon on the suction side, "dry" operation (without or with insufficient lubrication), too high pressures (over 30 bar), and high (over 90 °C) temperatures. The accumulated dirt (mechanical impurities) in the system leads to very rapid wear of the compressor, and it will be impossible to repair it.

Condenser or radiator

The condenser is a heat exchanger usually located in front of the engine radiator. The condenser is used to cool the coolant in the same way that a radiator cools your engine coolant. Capacitors are usually made of thin aluminum and are often damaged by excessive internal and external corrosion. External corrosion is most commonly caused by road salt and weather conditions. Internal corrosion is the result of system contamination, which we will discuss later.

Some steps you can take to improve cooling and extend the life of your condenser is to keep it clean. Use moderate pressure garden hoses to clean the surface and remove insects, debris, and road grime. Or ask the car wash employees to flush your car's radiator, just be sure to tell them to adjust the water flow. Otherwise, high-pressure water can squeeze the condenser fins.


The evaporator is the second heat exchanger in your vehicle's air conditioning system. It is located either directly at the firewall of your car or inside the car’s interior. This is the knot that makes the air cold. The evaporator is one of the largest compressor oil storage locations in the system. This is an essential factor in solving problems associated with the contamination of the car air conditioning system. The acids that form in the system mix well with the cooling oil. And if the evaporator contains a lot of such oil (usually 0.08-0.118 l), then it turns out that it contains a large amount of highly corrosive acids. This can lead to premature failure of your vaporizer.

Also, the drainage tube of this part for air conditioning often becomes clogged with dirt that gets through the air intake (leaves, poplar fluff, etc.), and the evaporator becomes the main breeding ground for bacteria, spores, and mold. Over time, they can become the source of a truly disgusting odor. One of the best odor control products is to use products that help decontaminate and clean the evaporator and that are applied to the surface of the evaporator. Spraying the ventilation ducts will only mask the problem without solving it.

Receiver-drier or accumulator-drier

Your system has one of these parts for air conditioning. Since they serve approximately the same function, the terms dehumidifier and accumulator are often used interchangeably.

  • The receiver-drier is installed on the discharge line between the condenser and the control valve.
  • Accumulator-drier is installed on the low-pressure side immediately after the evaporator and upstream of the compressor.

Functionally, they do the same job. There are no preventive measures for them. However, during maintenance, they are often left unattended. Yes, they cost money, but repairing a car air conditioner without replacing the filter drier is like using old oil filters on a new engine after replacing an old one. Sounds absurd? Yes. Does this happen every day? Yes, it happens, and much more often than people say.

Why is it so important to replace the filter drier?

For starters, see them as simple filters. Any filter, no matter what design, has a service limit. When your filter drier is clogged (by dirt from the system, corrosion, or moisture), the entire air conditioning system can be compromised because one element of the system is not functioning. Considering that the weight of moisture absorbers is getting lighter and lighter, it is recommended to change the filter driers every 3-4 years, even if the system has been working without interruptions.

How do the parts of the air conditioning system work together?

How do the parts of the air conditioning system work together?

The operating principle of the air conditioning system is quite simple:

  • The compressor compresses the gaseous refrigerant to 12-20 bar, which heats up to 50-80 degrees Celsius, and pumps it into the condenser.
  • In the condenser, freon is cooled due to good heat exchange with the surrounding air (incoming airflow when the car is moving or blowing with an additional fan when the car is stopped) and turns into liquid on the inner walls of the condenser.
  • Then the liquid freon enters the receiver-drier, where the refrigerant is filtered from dirt, dehumidified from water, and the liquid part is separated from the gaseous one.
  • After the receiver, the liquid freon passes through a small hole (expansion pipe), which causes the refrigerant pressure to drop sharply to 1-3 bar, and enters the evaporator.
  • The evaporator is the same condenser, only of a different shape. Its task is to ensure efficient heat exchange between the refrigerant and the air passing through the evaporator honeycomb. And when liquid freon with low pressure enters the evaporator, it begins to evaporate intensively and turn back into gas while cooling the evaporator itself to 0-10oС.
  • Gaseous freon at low pressure again enters the compressor, where it is squeezed, and the cycle is closed. A small amount of special oil is used to lubricate the compressor, which dissolves in the liquid refrigerant.
  • The heater fan of the passenger compartment pumps air through the cold evaporator, which is then cooled. The whole process is monitored by the control unit using several pressure and temperature sensors located in different parts of the system.

As you can see, everything is pretty simple. And this "refrigerator" would work like millions of household refrigerators for tens of years without any repairs, if not for constant vibration, temperature changes, humidity, and harmful environment.

Parts of air conditioning system breakdowns causes and diagnostics

Due to the fact that the device operates in rather difficult conditions (dust, dirt, vibrations, etc.), the air conditioning system is not insured against breakdowns. Most often, car owners are faced with the following manifestations of air conditioner malfunctions:

  • interruptions in work (unevenness);
  • weak air cooling in the car interior;
  • uncharacteristic noise both during the operation of the air conditioner and after it is turned off;
  • unpleasant odors during device operation.

These symptoms can have various reasons. Therefore, it is necessary to diagnose the device. First, you should collect basic data on the operation of the air conditioner. For this:

  • Start the engine and turn on the air conditioning system at full power.
  • Listen carefully extraneous noises may indicate that one of the important parts of air conditioning, the compressor, will have to be repaired or replaced.
  • Check the air coming out of the fan holes. Is it warm, cold, or the same temperature as the cabin? Is the temperature flow changing?
  • Change the air pressure indicators and check if the airflow changes accordingly.
  • Sniff the outgoing air if there is an unusual smell, it may be necessary to replace one of the secondary parts for air conditioning the filter in the cabin.
  • Check the fuses it is better to find the panel's location using the instructions since it can be in the trunk, under the hood, and even in the area of ​​the driver's legs.

Diagnose the airflow and other parts for air conditioning

  • Make sure that the air comes out of the holes that were selected. We move the regulator to another position and see if the stream has moved. If not, the air intake drive is probably faulty, and it is necessary to replace the curtains inside the instrument panel.
  • Look at the air filter in the cabin clogged debris and dirt can interfere with air pressure and be a source of unpleasant odors. In such cases, it is sufficient to replace these parts of the air conditioning system.
  • Increase the air temperature. If the airflow rate decreases, the fan may have a defective electromotor.

Diagnose the air temperature and next parts for air conditioning

  • Clean the front of the condenser (usually located at the front of the radiator). We carefully remove all dirt, leaves, fluff, and other debris.
  • Examine the compressor clutch. Most often, it is located just behind the radiator grill and looks like a small engine with a wheel at the end. We start the car and see if the wheel is spinning. If not, the compressor is defective.
  • Check the tension of the compressor belt. If it sags, it needs to be replaced.
  • Examine the hoses that connect the units of the air conditioner. If there are oil spots, a refrigerant leak is likely.
  • If the initially cooled air becomes warm, there may be an excess of air and moisture in the system, which froze the components. It is best to pump out or flush the system with a vacuum pump.

Self-determination of a malfunction is not a reason to cancel a visit to a specialist. We hope that our article has clarified the parts of the air conditioning system and you will help keep them in proper order. In case you are looking for parts for air conditioning, you can take advantage of our convenient service.

Automobile Air Conditioning Systems FAQ

Automobile Air Conditioning Systems FAQ
  • What are the major components of automobile air conditioning?

In general, the car air conditioner device includes:

  1. Compressor;
  2. High and low-pressure lines;
  3. Capacitor;
  4. Dehumidifier;
  5. Thermostatic expansion valve or throttle;
  6. Evaporator;
  7. Electrical equipment (temperature sensors, electric fans, electromagnetic clutch, etc.).
  • What is the basic principle of an automobile air conditioner?

The basic principle of an automobile air conditioner is the ability of liquids to absorb heat during evaporation and release it during condensation. That is, the car air conditioner absorbs heat by the evaporator (cools the interior with a stream of cooled air) and releases it into the environment where the condenser is located.

  • What is the most expensive part of an air conditioner?

The most expensive part of an air conditioner to replace and repair is the air compressor. However, prices vary from store to store. For example, on PartSouq, you can find parts for air conditioning at affordable prices.