Car Air Conditioning System Diagram And Maintenance

Car air conditioning system diagram – On a summer day, it turns out that the car’s air conditioning is not working, the most prestigious and comfortable car turns into hellish carriage. To avoid such unpleasant surprises, you must first perform timely maintenance on the air conditioning system. and also to make it work properly.

Then the air conditioning will delight you with coolness in the heat and comfortable humidity levels, even in humid weather. So, in this article we show a car aircon system diagram, or automotive air conditioner system, how car ac works with important components.

Table of Contents

Car Air Conditioning System Diagram

According to the principle of operation, car air conditioning is no different from a household split system installed in an apartment or office. Using the laws of thermodynamics, it transfers thermal energy from the cooled chamber to the environment.

Operation Principle

Coolant (aka “refrigerant” or “freon”) enters the compressor sleeves at a low pressure of 3-5 atm in an aggregated state of gas at a temperature of 10-20 °C.

The piston compressor, or scroll design, compresses the refrigerant to a high pressure of 15 to 25 atm. In this case, the gas temperature rises to 70–90 °C (you may have noticed how the hand pump heats up when pumping the tires—it is the same law).

The heated gas enters the condenser, where, as a result of this last active thrust, it cools and changes from the gaseous state to the liquid phase (with the release of additional heat).

From the condenser, still hot refrigerant flows into the thermostatic expansion valve (TRV). Its job is to control the freon supply to the evaporator circuit. At the outlets of the expansion valves, the temperature and pressure of the coolant are significantly reduced due to the fact that part of the coolant substance evaporates (you may have noticed that it is cold when it is sprayed from deodorant cartridges-it’s the same principle).

At the expansion valve, even at low pressure, the mixture of gas and liquid refrigerant enters the evaporator. There, all liquid freons enter the gas phase, and as heat is absorbed during evaporation, the air passing through the evaporator is cooled.

Finally, low pressure refrigerant gases enter the compressor sleeves – repeated cycles.

The main difference between car air conditioning and home air conditioning is the working conditions. Home appliances do not shake on bumpy roads during operation, and they have no specific restrictions on mass/efficiency ratio.

Therefore, in household air conditioners, thicker and heavier ducts (cooling pipes) are used, and the joints are more reliable and tight. But even if the home system needs to be serviced: refueling with freon and cleaning, this applies even more to car air conditioners.

Car Air Conditioning System Diagram And Maintenance — **Car Air Conditioning System Diagram**

As we already know, an air conditioner consists of a compressor, a thermostatic valve or valve (TRV), a condenser and an evaporator. The system also contains a fan, lines with seals, temperature and pressure sensors, and another very important component – a filter drier (receiver drier).

The purpose of the latter is to remove moisture from the refrigerant, which penetrates there from the atmospheric air during the operation of the compressor. More broadly, the system also includes curtains that redirect the air flow through the air ducts to blow different areas of the passenger compartment, and control mechanisms for them, as well as the cabin air filter.

Naturally, all of the above can break down – either due to natural wear and tear (resource depletion), or as a result of untimely maintenance or illiterate operation.

To prevent this from happening, it is necessary to follow a number of recommendations.

Recomendation For Car Aircon Maintenance

In addition to showing the car air conditioning system diagram, we also provide recommendations on how to care car air conditioners properly.

Refueling of freon Regularly

Contrary to the common misconception, when the air conditioner in the car does not cool, the point is most likely not that there is no freon left in the system. Even if the amount of refrigerant drops significantly, the air conditioner can continue to operate. However, this increases the risk of a more serious breakdown, which may occur before the refrigerant level leads to a permanent shutdown of the air conditioning.

To ensure uninterrupted operation of the air conditioner, you should refuel regularly, at least once every two years (and for cars over 6 years old – annually), and preferably after one refueling – completely refill the system (with oil change, cleaning from dirt and vacuuming to remove moisture ).

Generally, the newer the car, the more sensitive the system is to lower refrigerant levels. Old systems could work normally with a loss of up to 150 grams of freon.

And even when leaving up to 250 grams, they could maintain productivity. But in cars of relatively recent years of production, the loss of some 70 grams of freon is already fraught with compressor breakdown in the near future. It turns out that with a leakage rate of 35 grams per year, the critical service period is once every two years.

Where does the refrigerant go from the system? Normally, if the line connections are still “poisoned” and the seals have not yet leaked, it goes straight through the material of the pipes. As we remember, unlike a household refrigerator, which uses metal (copper or aluminum) tubes connected by soldering, the auto tubes are elastic. And for them there are leakage rates defined by international standards.

There are three tubing standards used in car air conditioners: the American SAE standard, the stricter German DIN, and the strictest Japanese JIS. These standards have been developed with an eye on the standard vehicle life: 5-6 years for America, 10-12 years for Europe, and up to 15 years in Japan. Naturally, cars last longer, but manufacturers do not take this into account when designing. By the way, this is another confirmation of the correctness of those who prefer Japanese cars.

Thus, the rate of decrease in the volume of refrigerant in systems with different pipes is not the same. An equal amount of freon (assuming the same length of tubes) will go away in approximately 1.5 years with SAE tubes, 2 years with DIN tubes and 2.5 years with JIS tubes.

Car Air Conditioning System Diagram And Maintenance

Car Air Conditioner maintenance for fault Preventively

After you know the Car Air Conditioning System Diagram and how Car Air Conditioning works, we also tell you how to maintain the AC as an effort to prevent unwanted damage.

You should use the air conditioner systematically – even in winter, it is necessary to turn on the climate control (and not only heating the cabin with hot air from the engine) for at least 10-15 minutes at least 2 times a month, and preferably 1-2 times a week.

If this is not done, problems with the tightness of the seals, which are lubricated and moistened with refrigerant during operation, will begin much more quickly. And with the onset of the June heat, it may turn out that the air conditioner does not work after the winter, although in August last year everything was in order and “did not bode well.”

After turning off the air conditioner, even if you do not need to go anywhere – do not turn off the engine immediately, let the stove run to dry out all the air ducts and channels of the evaporator.

IMPORTANT! It is possible to turn on the air conditioner in winter only after the passenger compartment has completely warmed up – only after that the air conditioner sensors and the entire system are able to work correctly.

#1. Condenser cleaning

Debris builds up on the condenser (cooling radiator of the air conditioning system), which impairs heat dissipation and the efficiency of the entire system, which increases the load on the compressor.

As a result, the climate control begins to automatically turn off, because due to overheating in the system, the pressure rises above normal. In addition, metal begins to corrode under a layer of dirt – even aluminum is susceptible to acid corrosion.

If, when driving in traffic jams, when there is no free-flow blowing, the air conditioner in the car suddenly stops working, but after a while, when driving at speed, it can be started, it is urgent to clean the condenser. This can be done at the sink, but care must be taken not to damage the structure of the radiator.

#2. Condenser external cleaning rules:

Direct the stream of water strictly at right angles;
Do not bring the spray of the high-pressure apparatus closer than half a meter to the car;
A dense crust of dirt must first be softened with a radiator cleaner.

#3. Replacing the filter drier

The filter drier (receiver drier) is designed to absorb moisture and clean freon from compressor wear products. According to European standards, it has a resource for the entire life of the car, that is, 7 years, maybe a little more.

But this calculation is made with the condition of year-round use, otherwise the resource is sharply reduced. If the filter resource is exhausted, that is, the absorbent has absorbed as much water as it could, the symptoms will be a spontaneous shutdown of the air conditioner and freezing of the hoses.

#4. The 4 main functions of the receiver dryer:

Freon cleaning from wear products;
Separation of the gaseous refrigerant from the liquid phase;
Absorption of moisture (water) penetrated into the system;
Storage of the refrigerant stock in the filter drier tank (depending on the operating conditions of freon in the system, more or less is required).

If the system was opened for repair, replacing the receiver-drier is definitely necessary, without exception. If this is not done, water will collect in the system, it will be driven into the compressor, and the incompressible liquid that gets into it will lead to a water hammer and its complete breakdown literally for the next 200-500 km.

IMPORTANT! Modern filter-driers, which use a zeolite absorbent, do not lend themselves to any regeneration by evacuation or heating (old filters with silicogel could be somewhat “updated” in this way). Zeolite binds water chemically, and this is an irreversible process.

#5. Antibacterial treatment

In the honeycomb of aluminum evaporators, with the constant presence of atmospheric moisture condensate, fungi and bacteria multiply. The result is an unpleasant odor. Even the cold air feels heavy, like in a basement. Initially, the evaporator has an antibacterial coating, but over time it degrades and an antibacterial treatment becomes necessary.

There are several options for antibacterial treatment of the evaporator:

Special aerosols that are sprayed in the cabin with the windows tightly closed and the air conditioner turned on for the whole in recirculation mode.

Foam sprays are injected directly into the air duct system (after such a procedure, you cannot use air conditioning and ventilation for a couple of weeks, and you must drive with an open window so that chemicals do not harm the driver’s health). Since there are dead zones in the system and in the evaporator itself, where aerosols and foam do not get, the effect will last from six months to a year.

The use of ozonizers is safe for the driver and passengers, but gives an even shorter-term effect – no more than 2-3 months.

The most radical and effective option is to dismantle the evaporator with complete cleaning.

If the efficiency of the system has clearly dropped, despite the fact that the freon refueling was carried out on time, the condenser is not covered with dirt, and the system itself does not turn off – most likely, the matter is in the evaporator. And if water appears on the floor in the cabin, it’s definitely in it.

Other Car Air Conditioner Checks

Car Air Conditioning System Diagram And Maintenance

Cabin filter. A dirty air filter in the passenger compartment, obstructing the free flow of air, reduces the efficiency of the system and increases the load on it. And it can also be a source of unpleasant odors. The filter should be changed at least after 15 thousand kilometers.

Compressor drive. If the air conditioner blows in the car, but does not cool, you should inspect the compressor clutch and drive belt. We start the car and the air conditioner and see – if the drive pulley does not rotate, then the reason is either in the weakened belt or in the clutch.

Faulty expansion valve. Cyclic operation of the air conditioner, the flow of cold air intermittently, freezing of the evaporator hoses, spontaneous shutdown are signs of a malfunction of the thermostatic valve. The reasons may be: mechanical damage, improper adjustment, internal contamination of the system, the presence of water or air in it.

Condenser fan defective. If the fan works with a lot of noise or does not rotate at all, you need to urgently fix the problem. The point is either the wear of the bearing, or in the absence of rotation, the cause may be a violation of electrical circuits (relays, brushes, contacts, fuses) or mechanical damage.

Pressure sensor malfunction. In case of unstable operation and spontaneous shutdown, the reason may be a sensor malfunction, the function of which is to turn off the system at critical values of the refrigerant pressure readings. The prerequisites for a malfunction can be both mechanical (contamination) and electrical (fuse, contacts, relay).

In general, in the business of servicing an automobile air conditioner, it is important not to try to deceive the laws of physics in pursuit of economy.

Of course, if we want to drive the car in thermal comfort, despite the heat and traffic jams, we must do everything that is recommended. Otherwise, the cost of repairs can easily exceed $ 500. And then you will have to fork out, admitting that the air conditioner in the car broke down precisely through our fault.

Car Air Conditioning System Diagram

Operation Principle

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