The heating (air conditioning) and ventilation system is a single complex that provides the most comfortable conditions in the car regardless of weather conditions and driving mode
The system includes a heater (increases the air temperature in any operating mode of the system), an air conditioner (reduces the temperature and humidity of the air, is installed depending on the vehicle configuration), an air blower, air ducts with a filter (provide air exchange in the cabin, clean the air from dust) and a control unit (controls all elements of the system to obtain the specified comfort parameters).
The car is equipped with a liquid-type cabin heater.
The heater radiator is connected to the engine cooling system by two hoses passing in the engine compartment.
The radiator is placed in a plastic casing of the climate control unit, installed under the central part of the instrument panel.
Main heater components:
- – heater radiator 6, designed to heat the air entering the passenger compartment with heat from the engine cooling liquid;
- – air blower 11.
The electric motor 12 of the air blower with excitation from permanent magnets provides an adjustable supply of outside air to the heater and air conditioner flaps.
To obtain different values of the air blower rotation speed, a block of additional resistors is installed in the power supply circuit of the electric motor;
– flap 15 of the temperature regulator of the air entering the passenger compartment from the heater. The amount of air passing through the heater radiator and outside air bypassing the heater radiator depends on its position;
– flaps 2 for distributing air coming from the heater through the air ducts into the passenger compartment or for blowing the windshield.
Air conditioning system design
In the variant version, the vehicle is equipped with a compressor-type air conditioning system.
The heater and air conditioner evaporator units are combined in one block.
The air conditioning system controls are located in the same block as the heater controls.
The basic diagram of the refrigerant movement in the air conditioning system is shown in the figure.
The compressor is mounted on the engine cylinder block and is driven by a V-belt.
The compressor ensures the circulation of the refrigerant in the system.
The compressor shaft is installed in the aluminum front cover of the housing on bearings and is sealed on the drive pulley side with a seal.
Compressor drive pulley 2 is mounted on a double-row ball bearing and rotates constantly when the engine is running.
When the air conditioner is turned on, torque is transmitted from the pulley to the compressor rotor through a friction clutch with an electromagnetic drive.
If the system is in good working order, a click is heard when the air conditioner is turned on - this is the pressure plate 1 of the clutch, under the action of an electromagnet, engaging with pulley 2 of the drive, and the compressor rotor begins to rotate.
However, the following compressor malfunctions may occur during operation of the air conditioner.
If, when the air conditioner is turned off, the clutch makes extraneous sounds during rotation, heats up, or a burning smell appears, then its bearing has probably begun to deteriorate.
In this case, it is necessary to replace the bearing.
In some advanced cases, it may be necessary to replace the compressor clutch assembly or its components parts.
If you do not hear a click after turning on the air conditioner, the following problems may be occurring:
- – there is a refrigerant leak and the control system is blocking the compressor from turning on;
- – the pressure sensor in the system is out of order;
- – faults in the electrical circuits of the control system;
- – the winding of the clutch solenoid coil has burned out;
- – the engine control unit has blocked the compressor from turning on for some reason (high engine coolant temperature, high engine speed).
If the clutch rotates easily and freely, but when you turn on the air conditioner, extraneous noises are clearly heard or even the engine stalls, then most likely the compressor has jammed.
The internal pump part of the compressor cannot be repaired. In this case, the compressor will have to be replaced.
And the last, most unpleasant option.
A click is heard, the clutch easily rotates the compressor shaft, but the air in the cabin does not cool. In this case, the compressor runs idle, without pumping anything.
This malfunction can only be determined by an experienced specialist with special control and diagnostic equipment.
The most accurate determination of the cause of the malfunction can be made after a complete diagnosis in a specialized service center for the repair of automotive air conditioners.
The condenser (air conditioner radiator) is a multi-flow type located in front of the engine cooling system radiator.
It is attached to the radiator frame with four brackets.
The condenser cells are made of flat thin-walled aluminum tubes with internal longitudinal partitions for rigidity and external fins to improve heat exchange.
Aluminum tanks with flanges for connecting pipelines and a receiver
The tanks are divided into sections by height, so when passing through the condenser, the refrigerant flow changes direction several times
Condensation occurs in the condenseration of vapors of the refrigerant compressed by the compressor and the removal of the heat released into the surrounding air.
When the air conditioner is turned on, the engine control unit turns on the power supply circuit of the electric fan of the engine cooling radiator, which improves heat exchange in the condenser and reduces the pressure in the air conditioning system.
At least once a year, preferably before the start of summer operation, wash the fins "A" of the condenser honeycomb from adhering dirt, dust and anti-icing reagents "B".
This will improve heat exchange, will reduce the pressure in the system and increase the service life of the system elements.
Do not use washing machines with a high-pressure water jet to wash the condenser. This may damage the "B" thin-walled fin plates.
Even with regular washing, the need to replace the condenser arises much more often than we would like.
The fact is that it is the first to take on the flow of anti-icing reagents, dirt and pebbles from the road. And the walls of its tubes are thin.
In most cases, the condenser is damaged by corrosion in the third or fourth year of operation.
If the condenser is damaged due to corrosion, then repairing it will be more expensive.
Even if an argon welding specialist manages to patch the hole, a leak may soon appear in another place. The pressure in the system on hot days can reach 25-28 bar.
In addition, you should take into account the complex structure of the condenser tube: it is divided into channels by partitions along the length, so there is a high probability that after welding, some of the channels will be blocked.
Accordingly, the dissipated power will drop and the operation of the air conditioner will deteriorate, especially in traffic jams and in hot weather.
After each experiment with patching the condenser, you will need to pay for removal and installation, welding of the condenser and filling the system with refrigerant. So it is better to install a new condenser right away
The evaporator is located in the heating (air conditioning) and ventilation system unit in the passenger compartment.
The evaporator is made of aluminum tubes with external finning to improve heat exchange.
Passing through the evaporator tubes, the boiling refrigerant actively absorbs heat from the air blowing on the outer finned surface of the tubes. The air is cooled and supplied to the car interior by the air blower.
When the air passing through the evaporator is cooled, the water vapor contained in it condenses.
The condensate drains under the bottom of the car through a drain pipe located on the lower part of the right side of the body panel.
If the ambient air is highly humid, a puddle of water may form under the car, which is an indirect sign that the air conditioning system is working properly.
When operating the car on wet particles of road dust and dirt settle from the condensate on the outer surface of the evaporator.
This layer becomes an excellent environment for the life and rapid reproduction of putrefactive bacteria and fungal cultures
Over time, an unpleasant odor appears in the car. It is especially noticeable when the air conditioner is turned off and in humid weather.
In order to minimize the risk of this problem, when buying a new car, it is necessary to carry out preventive treatment of the evaporator with special chemicals, regularly replace the cabin filter and clean the drain pipe
If, despite the measures taken, the smell still appears, contact a specialized service for repairing car air conditioners for disinfection or washing the evaporator
If the contamination is very severe, the evaporator will have to be replaced.
On the side surface of the evaporator there is a flange for attaching the thermostatic valve.
The block-type thermostatic valve is located in the evaporator body.
The valve is attached to the pipelines and the evaporator using flange connections
After passing through the throttling hole in the valve body, the liquid refrigerant sharply reduces its pressure and begins boil
A control element is installed in the valve body, changing the flow section of the throttling hole depending on the pressure and temperature of the refrigerant
Control the element is adjusted at the factory and cannot be adjusted during operation.
The receiver-dryer is installed on the condenser on the left side and forms a non-separable unit with it.
Inside the housing there is a filter element (cartridge) filled with desiccant granules (silica gel)
The liquefied refrigerant passing through the receiver is cleaned of possible impurities, dirt and moisture. There is a hole in the lower part of the housing for replacing the filter element.
In case of repair or replacement of air conditioning system elements, if it was in an open state (any units were removed, pipelines were destroyed, etc.), the receiver-dryer cartridge must be replaced.
Otherwise, after filling the system, the refrigerant will not be dried and acids may form inside the system, which will destroy the air conditioner parts from the inside.
The pipelines connect all the elements of the air conditioning system into a single sealed circuit.
The pipelines and their mounting flanges are made of aluminum alloys.
Protect metal sections of pipelines from dents and kinks. Any narrowing of the flow cross-section of the pipeline leads to a decrease in the system's performance.
To connect mutually moving elements of the system, the pipelines in some sections are equipped with flexible inserts made of synthetic materials.
At the junctions of individual elements of the system, neoprene circular cross-section sealing rings are installed.
When repairing the system, when disconnecting sections of pipelines, the sealing rings must be replaced.
Tighten the threaded connections of the pipelines to the recommended torque.
Weak or excessively strong tightening leads to deformation of the sealing surfaces and leakage of refrigerant.
Service valves for connecting diagnostic and filling equipment are located on the pipelines.
The valves are covered with threaded caps to protect them from dirt.
The valves are equipped with valve spools similar in design to the valve spools of wheel tires, but differ from them in size.
A special key is used to unscrew and screw in the valve cores.
It is prohibited to check the presence of refrigerant in the system by pressing the service valve cores, since after such a check the valve core may not close completely and refrigerant will leak from the system!
The pressure sensor is installed in the engine compartment on the high-pressure line section.
Based on the sensor signals, the engine control unit switches off the air conditioning compressor in the event of a depressurization of the system or an emergency increase in pressure in it in order to protect the compressor from overloads.
The control unit for the heating, air conditioning and ventilation system is installed in the instrument panel.
Refrigerant
The system is filled with HFC-134a (R-134a) refrigerant. The total filling volume is (450±25) g.
Special oil FD 46XG (PAG) is added to the refrigerant to lubricate the compressor. It is strictly prohibited to use refrigerants and oils of other types in the system.
During the operation of the car air conditioner, situations periodically arise when the air conditioning system needs to be serviced or repaired.
Modern diagnostic and repair equipment is used for this. The most common situation is a system depressurization and refrigerant leakage.
Highly sensitive halogen leak detectors with sound indication are used to detect leaks.
In some complex cases, the so-called ultraviolet diagnostics of the air conditioning system tightness method is used.
The method consists of introducing a special dye into the system in microdoses.
In places of micro leaks, the dye, together with the refrigerant, gradually comes out onto the outer surface of the system elements.
During the inspection of the system, the dye begins to glow (fluoresce) under the ultraviolet rays of a special lamp and the refrigerant leaks become visible.
It should be noted that the dye does not have any negative impact on the system.
It can be in the refrigerant and circulate through the system for as long as you like and serve its purpose only when a leak occurs.
After repairing the air conditioner, it is necessary to vacuum and fill the system with the appropriate refrigerant (R-134a).
The volume of air conditioning for each car model is individual.
To carry out high-quality refueling of the car air conditioner, you need:
– precision manometric blocks with special connecting tips;
- – two a step vacuum pump for complete removal of air and water vapor from the system;
- – high-precision (division value of no more than 5 g) scales for dosing the refrigerant being filled.
Due to the specific features of air conditioning system repair, this section describes only the work on removing and installing individual elements and the system control unit.
Work related to filling the system with refrigerant should be carried out in specialized service centers.
The air conditioning system is filled with refrigerant under high pressure.
Liquid refrigerant getting on human skin causes severe frostbite, therefore, if possible, all work related to servicing, repairing or dismantling air conditioning system elements should be carried out in specialized service centers equipped with professional technological equipment. When carrying out work on your own, take precautions.
Ventilation system design
The vehicle uses a supply and exhaust ventilation system.
Outside air can enter the passenger compartment through the door windows when the windows are lowered and through the air blower grille located in front of the windshield.
Air from the air blower is supplied through air ducts into the vehicle interior through the windshield blower nozzles, side and central nozzles, and also through the lower nozzles of the heater housing.
Exhaust ventilation is carried out through a grille installed in the trunk of the vehicle
When placing loads in the trunk, try not to block the ventilation grille if possible. Leave a small gap between the luggage and the trim panels.
Efficient operation of the exhaust ventilation improves the temperature in the cabin and reduces condensation on the window glass.
The exhaust ventilation holes are covered from the outside by deflectors with petal valves, which are installed in the rear of the body, in the cavity of the rear bumper.
Safety precautions when servicing the air conditioning system
The refrigerant is a chemical compound that requires careful handling to avoid harm to health.
It is necessary to work in a well-ventilated area and avoid inhaling refrigerant vapors.
When performing work related to depressurizing the air conditioning system, it is always necessary to wear safety glasses and wrap fittings, valves and connections in a clean cloth.
It is prohibited to carry out welding work on the car near the units and pipelines of the air conditioning system.
It is prohibited to bend flexible pipe inserts (hoses) with a radius less than four diameters of the flexible inserts.
Regularly inspect the hoses for cracks and abrasions.
Before disconnecting the air conditioning system pipes, remove all refrigerant from the system.
Unscrew the threaded connections of the system components slowly. Keep your face and hands away from the disconnection point to avoid injury if there is residual liquid refrigerant in the system.
If pressure is detected in the system while disconnecting the pipes, remove the refrigerant from it.
Immediately after disconnecting any section of the system, cover the openings with caps or tape. This will prevent moisture and dirt from entering the system, which can cause failure of the pump part of the compressor.
