Some car owners believe that the air conditioners in their cars will work properly for many years. They are sure: since refrigerators of the times do not break for 50 years, then equipment with a similar purpose will last almost forever. But there is one problem: the operation of air conditioners in the car is complicated by the fact that these devices operate in conditions of sharp temperature changes. In addition, the air they purify is highly polluted, its humidity is elevated. As a result, repair of HVAC equipment is inevitable. In today’s article, we will analyze how to diagnose an air conditioner.

A little history of car air conditioners

Climatic installations for cars began to be used before the Second World War. Their cost reached one third of the price of the vehicle.

Already in 1933, split systems were used in every home in the United States. In 1936, scientists began to create air conditioning for cars. For the first time they began to place them in passenger trains. The equipment operated on the same principle as the refrigerator.

For the first time, an air cooling system was installed on a Packard Car. The decision was expensive, so the price of a car was $ 700. Of these, 274 dollars (that is, a third of the cost of the car) was spent on installing an air conditioner. The disadvantage of the old type of climate system was that it was huge and occupied half of the luggage compartment. There was no automatic control. Obviously, such car air conditioners did not become popular and ceased to produce them. But already in 1941, climate systems were re-developed by the Cadillac auto giant.

With the outbreak of hostilities, research was suspended. The company returned to development when the war ended. Already in 1954, a breakthrough was made in the creation of air conditioning systems for automobiles. For example, Kelvinator installed both ventilation and heating on their machines. The dimensions of the climate control system were small, it was located in the engine compartment. Over the years, these devices have gained popularity among consumers. Since that time, the principle of functioning of the air conditioner has not changed.

Top 3 most common car breakdowns:
  1. Dashboard Warning Icons: Engine Check Indicator The “Engine Check” icon on the dashboard is the most common problem for cars and trucks. This indicator on the tidy lights up when the computer (electronic engine control unit) detects an error code in the system in the operation of any system. In total, there are more than 200 possible error codes, in order to identify the cause, you need to do a full-fledged electronic diagnostics in the car service nearest to you (most often it is free).
  2. High fuel consumption When the engine is operating normally, it burns fuel at a speed that helps to efficiently consume fuel (we get fuel economy). However, some parts of the fuel system, such as fuel filters, air filters, mass air flow sensors and oxygen sensors (lambda probe), become dirty and worn out over time. If they are not replaced (and this is the most common reason for increased fuel consumption), then this will lead to the fact that the engine will consume more fuel than usual.
  3. Squeaking brakes Brakes in a car are sacred. It is from them that the safety of our car, and sometimes life, often depends! Therefore, when you notice any signs of problems, such as a squeal, a creak, or if, for example, the brake pedal becomes soft, you should, of course, show the car mechanic as soon as possible. Most often, a creak or squeal suggests that it is necessary to replace brake pads or brake discs. Some car breakdowns are not critical and allow you to operate the car, while others, on the contrary, require immediate intervention. Since 1990, in the United States, almost all cars are equipped with climate systems. Since 1960, the simplest devices of this type have been used on trucks.

The principle of operation of the air conditioner

The climate system for the car consists of several installations that create and maintain a given climate in the cabin. For example, you can control humidity, air temperature, clean it, and also regulate the strength and direction of air flows. Air conditioning creates a favorable micro-climate, so everyone in the car feels good.

This device cools the air flow coming from the deflector by 5–10 degrees or even more, depending on the power.

Thanks to the built-in electronic sensors, modern air conditioners for cars allow you to choose the exact temperature regime, as well as adjust many parameters. The device not only makes the air colder, but also removes excess moisture from it. This is necessary so that the windows in the car do not fog up in rainy weather. Car air conditioning not only makes driving safe and comfortable. Using the climate system, you can create ideal conditions for everyone who is in the car.


The attention and speed of the driver’s reaction depend on the micro climate in the cabin. If the car is hot, stuffy and humid, it will be dispersed, as a result of which an accident can occur. This was confirmed not only by scientists, but also by statistical data: the hotter the street and the higher the air humidity, the more traffic accidents occur.

If you turn on the air conditioning, the well-being of the driver and everyone in the car will become better, which means that the risk of an emergency will decrease. Obviously, the costs of climate control will be justified, because the life and health of the driver and passengers are priceless.

The operation of an air conditioner is similar to the operation of a home air cooling system. Recall physics: when a substance evaporates, then heat is absorbed. If it condenses, then thermal energy is released.

The climate system starts with the compressor: after pressing the start button of the device, the clutch starts on it and pulls the pulley with the transmission belt from the engine.

Do not forget that the air conditioner functions when the engine is started. As soon as the clutch starts to operate, the compressor turns on and the pressure increases.

In the air conditioning system, the refrigerant is under high and low pressure. Compressed refrigerant comes from the compressor, and at low pressure it enters it.

The refrigerant moves from the compressor to the condenser, due to the action of the fan and the air flow, the refrigerant is cooled, which is then sent to the dryer. Here the refrigerant is drained, dust is removed from it. After that, it goes to the evaporator.

The system has many other sensors and devices. For example, a fan for blowing, ventilation system, various regulators. When the car is equipped with climate control, you can find a whole range of additional devices. There are systems with many evaporators, depending on the structure of the ventilation system in the machine.

The evaporator releases low pressure refrigerant, it enters the compressor again, and the process repeats. We will not talk about all kinds of additional devices, because in different models of cars they differ. Just remember that the principle of functioning of climate control and air conditioning in the cooling system is the same.

Diagnostics of the air conditioner + common malfunctions

When there is a liquid substance in the system, it is necessary to ensure complete tightness. Otherwise, Freon will pour out, and the air conditioner will become worthless. But during operation of this device, depressurization sometimes occurs. The fault is the irresponsibility of the mechanics, which leads to the leak of Freon. Each car mechanic will confirm that repairing or refueling an air conditioning system is not an easy job that only an experienced specialist can do. Therefore, the diagnosis of a car air conditioning compressor with your own hands can be performed only after studying the theory and gaining practical skills.

The problem is not only due to Freon leakage. For example, a malfunction of the condenser can lead to damage. It is also called an air conditioner radiator, because by the principle of operation it is similar to a motor radiator, only it has other functions.

When the condenser does not cope with its work, an air stream enters the inside of the machine, the temperature of which is the same as outside. This can happen because dirt has accumulated in the radiator. As a result, cooling is poor, and the climate system shuts down by itself. In no case should you procrastinate with repair work. It is necessary to clean the pollution, otherwise the radiator will overheat, and the pressure in the system will become extremely high.

The next most frequent failure is the failure of the evaporator. The reason is the appearance of corrosion if the device is dirty (or the tube through which moisture is removed is clogged). How to determine what the problem is in the evaporator? The air conditioner will not only work poorly, but water will appear in the car, an unpleasant odor will begin to be felt in the cabin.

If the master refills the air conditioning system incorrectly, moisture will no longer be removed, as well as dirt that penetrates the receiver (due to compressor wear).

When the master refueled or diagnosed the car air conditioner and the Freon got dirty, the filter will deteriorate and become unusable. As a result, the hoses of the air conditioner will freeze, because water stagnates in them. As a result, the air conditioning system will turn off.

Thermostatic expansion valve is also an important element that affects the functioning of the climate system. Indeed, thanks to the expansion valve, control is carried out over how much refrigerant is supplied. For this, it is necessary to take into account temperature indicators and pressure in the system.

During the diagnosis of the air conditioner by pressure gauges, it turned out that the thermostatic valve is broken? Be prepared for the following:

  • the air conditioning system will work cyclically, interruptions in the supply of chilled air will occur;
  • the evaporator hoses begin to freeze;
  • the air conditioner will turn off.

Why can such a breakdown occur? The point here may be as follows: mechanical damage to the valve, improper choice of the mode of operation of the system, pollution of the air conditioner from the inside, air and moisture entering the system.

When diagnosing an air conditioner, it can be revealed that it periodically turns off and is unstable. The reason is a pressure sensor malfunction. It is necessary that the cooling system shuts down if the pressure exceeds the permissible values. Sensor failure occurs due to contamination, improper operation of electronic components (contacts, relays, fuses).

The air conditioner condenser can be equipped with a fan so that the refrigerant cools. When the fan breaks, it starts to make extraneous noises or even stops spinning. This can happen because the bearing is worn out or the electrical connection is broken. The fan can also break as a result of mechanical damage.

The reason for this is the improper operating conditions of both the machine and the climate system. For example, overheating may occur as a result of:

  • driving a car in the heat, when climate control is not only unable to cool the air, but also warmed up to the limit;
  • overspeed driving (increased engine speed). As a result, the engine compartment overheats, as does the interior;
  • prolonged exposure to the car in direct sunlight (it becomes too hot inside).

Carrying out self-diagnosis of the air conditioner, visually assess the status of the device without disassembling it. So you can find mechanical damage. But even if everything seems normal at first glance, the problem can be serious.

Leak check

The most common malfunction is a leak. First of all, you need to find it. Previously, specialists searched for a leak using a small gas burner.

When the flame comes into contact with Freon, a green glow could be seen. This is explained by the specific properties of the refrigerant. This search method is ineffective, in addition, it can be harmful to health, because when Freon is burned, a toxic substance is formed – phosgene.

Today, there are 2 ways to detect leaks. For example, a device is used that finds freon vapors in the air. The sensitivity of the device is so high that even a small leak (5-10 g per year) can be detected. On sale you can find many simple electronic searchers. Everyone will be able to use this device for diagnosing an air conditioner. However, there are also more complex models of electric detectors, which only a specialist can work with.

Unfortunately, it is not always possible to detect a leak. The fact is that the electronic finder only finds a freon cloud. But you don’t know exactly which tube is flowing. And if the model of the air conditioner is such that the tubes are close to each other, then only an experienced auto mechanic can find the leak. It is possible to exclude a leak in one of the tubes by taking off and checking each of them in turn.

Diagnostics of an air conditioner with an electronic finder sometimes does not bring results. It also happens that freon disappears in 2-3 months (at a pressure of a certain strength). Also, if leaks are located nearby, the detector will signal that there is a leak, but in which place it cannot be determined. Then you should check using an ultraviolet lamp and dye. Pre-fill the system with oil and freon, and then fill in a special mixture that glows if you send ultraviolet light to it.

The coloring matter does not adversely affect the functioning of the air conditioner. Many car manufacturers pour this mixture into the system already at the stage of car assembly.

If it seems to you that the air conditioning system is not doing its job, drive the car into the garage, and then ultraviolet all the tubes and highways. You will immediately find a leak, because the resulting freon will glow a bright yellow color.

However, this diagnostic method has disadvantages. For example, to get to all the tubes, you have to disassemble the air conditioner. The hardest thing is to get access to the evaporator, because it is located in the dashboard. An alternative is to check the drain pipe. If you cannot do this, then use the electronic leak finder.

Compressor check

To diagnose the air conditioner, make sure that the compressor is functioning properly. If the device does not work efficiently, you will immediately understand this – the car will make extraneous noise. Another option for checking this device is to turn on the air conditioning system, and as soon as the compressor starts working, grasp the metal assembly behind the highway. After 2-3 seconds, you will feel that the handset has become cold.

If you think that you have an ice floe in your hands, then the compressor is in order. If the cold is unbearable, the device works as efficiently as possible. Then you should check the electrical components of the air conditioner: all kinds of couplings, sensors, fans.

Leak test

A simple diagnostic method that allows you to determine how much freon is flooded. What needs to be done? Look through the window next to the dehumidifier. Freon is white, is bubbling? A thorough diagnosis of the air conditioner should be carried out, as well as refueling it. Is the refrigerant transparent, uniform? Then everything is all right.

Pressure check

To measure the pressure, use the special equipment for diagnosing the air conditioner – a manometer. The manometer station is equipped with an adapter for tubes. We find in the engine compartment a thick line, there the pressure will be minimal.

We remove the plugs, insert the adapter, wiping the junction in advance. Then we unscrew the faucet on the manometer, let the second one remain closed – so you exclude the leak of freon. Now you need to start the car and find out what pressure in the system. The optimal indicator is 250–270 kPa.

You did not manage to diagnose the air conditioner with your own hands and identify a malfunction? We advise you to go to the service station, where professionals will detect and eliminate the breakdown.

Only in time to detect and correct the problem, you can avoid expensive repairs. Diagnostics of an air conditioner in a technical center is a system check during which you can find breakdowns, as well as decide how to repair a car.

It’s time to visit the service station to diagnose the car air conditioner if:

  • the cooling system does not cope with work, it is hot in the car;
  • hoses freeze;
  • the air conditioning system is not working;
  • after turning on the climate control, an unpleasant odor appears in the car;
  • oil stains occur under the air conditioner;
  • the fan does not work;
  • chilled air flow does not enter the cabin continuously;
  • the air conditioning is noisy.

A regular inspection – once every 6 months – reveals that the elements of climate control are contaminated, the system has ceased to be airtight, refrigerant penetrates through cracks and crevices.

Diagnostics of the air conditioner at the service station is as follows:

  • The master inspects the device, determines how worn the drive belt, bearings, pulleys, whether there are breakdowns of the highway, excesses.
  • Then the car mechanic checks for extraneous sounds that indicate the breakdown of the bearing and compressor elements.
  • The next step – the mechanic determines how clean the air conditioner is. There should not be an unpleasant smell, fungus, mold, pollution.
  • The master looks to see if there is enough refrigerant in the system.
  • The specialist determines the malfunction.

Diagnostics of an air conditioner in a car service takes 1-2 hours. The time depends on the type of breakdown.

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The cost of diagnosing an air conditioner may vary depending on:

  • type of car;
  • vehicle models;
  • places of diagnosis;
  • complexity of failure;
  • applied methods of inspection and repair;
  • the need to use special equipment;
  • how prestigious the service center is;
  • qualifications car mechanic.

To detect a serious malfunction, you will need to use several methods for diagnosing an air conditioner. The mechanic will spend a lot of time on this work, therefore the price of services will increase. If a car service has just opened and it has a small client base, then visual diagnostics will be free. If the company is well-known, the cost of verification will be quite high.

During the diagnosis of the car air conditioner, sometimes it is necessary to disassemble the device case. To find a breakdown, the following methods are used:

  • Visual inspection
  • Soap check.
  • Diagnostics using ultraviolet radiation.
  • Check with a halogen leak detector.
  • Immersion in water under pressure.
  • Flame check.
  • Diagnostics using compressed air.

Car air conditioning can be diagnosed in any car service. However, no one guarantees that a highly qualified specialist will provide you a  good service. How to choose the right service station? See what equipment is used there. It must be new, the only way it will be possible to carry out inspection and repair quickly. The better the work is done, the higher the cost. In addition, the car service must provide a guarantee for its services.

It is not necessary to visit a specialized service to check the cooling system. You can contact a private car mechanic. But how do you know the qualifications of such an employee? So that the diagnosis of the car air conditioner is carried out efficiently, ask your friends and acquaintances for the contacts of a trusted master. The price of his services will be less (compared to the service station). However, a private master will not provide a guarantee for work.

6 common myths about the dangers of car air conditioning

Every year, with the onset of the summer season, every car owner recalls stories about air conditioners. Let us examine which of these horror stories are true and which are not. And also consider whether the use of climate control can be harmful and how to avoid unpleasant consequences in any case.

Myth 1 . Using the air conditioning system, you can catch a cold.

It’s really possible to get sick, and for sure you checked it on yourself. If you want to ride with the air conditioning turned on and feel good, then adhere to the following rules:

  • Do not reduce the temperature sharply. The cabin should be cooler than the outside, not more than 10 degrees.
  • Direct the air flow to the windshield or to the legs, but not to the face.
  • When the air conditioning system is working and the car is moving, you cannot lower the windows. Otherwise, a draft is formed, and you can get sick.

Myth 2 . Hazardous microorganisms breed in the air conditioner.

When the cooling system is operating, condensation builds up in the radiator. In a humid environment, dangerous microorganisms multiply. The filter is clogged with dust, bacteria also develop in it. As soon as climate control is turned on, microbes enter the salon, and a person inhales them together with air. Because of this, in rare cases, pain in the eyes or conjunctivitis may appear.

But this can happen only if you are irresponsible with the state of your car. After all, the climate system should be periodically cleaned, filters should be changed, and the air conditioner should be diagnosed so that harmful microorganisms do not develop.

Myth 3 . If you use a cooling system, you can poison yourself with benzene.

According to the results of the studies, when the temperature in the car is above 16 degrees, benzene begins to stand out. The car air conditioner facilitates its movement around the cabin, and passengers inhale dangerous substances. It is scientifically proven that benzene harms the internal organs of a person, is the cause of the development of cancerous tumors.

To eliminate such negative consequences of using climate control, ventilate the machine for 2-3 minutes before starting to move. With the air conditioner running, periodically lower the windows for a couple of minutes.

Myth 4 . If the climate system works, the car consumes much more gasoline.

Indeed, fuel consumption rises by 10%. However, if you do not turn on the air conditioner while driving, but simply open the windows, the car “eats” 20% more. Therefore, using the air conditioning system, you save.

Myth 5 . Freon is harmful to humans.

Today, R134a refrigerant is used, which does not pose a danger to life and health. However, if freon is in contact with the flame, then poisonous phosgene is released. But even if an accident occurs and the air conditioning system is damaged, the refrigerant will not harm a person, because he is in the engine compartment and not in the passenger compartment – freon or phosgene will simply disappear.

Myth 6 . A working air conditioner reduces performance.

Dry air negatively affects the driver – a person becomes inattentive, quickly gets tired. Some argue that if climate control works, you can even fall asleep while driving. Avoid this situation will help regular ventilation of the cabin (the cooling system is better to turn off). If you have a long trip, make stops to relax.

The climate system can and should be used. Scientists have proven that if the cabin temperature is 27–37 degrees, the likelihood of an accident increases by 5–35%. When you use the air conditioner, you not only move comfortably, but also reduce the risk of an accident.