Scheme of air movement in the heating, ventilation and air conditioning system: 1 - air duct for blowing side windows; 2 – an air duct of an obduv of a windshield; 3 - air duct side and central deflectors; 4 - air distribution damper on the windshield or deflectors; 5 – an air duct of the conditioner; 6 – the top damper of distribution of air; 7 - lower air distribution damper; 8 - heater radiator; 9 - damper of the temperature controller; 10 – evaporator heat exchanger; 11 - fan guide casing; 12 - fan motor; 13 - damper of the recirculation system
The car can be equipped with either a ventilation and heating system or a ventilation, heating and air conditioning system, which serve to create the most comfortable conditions for the driver and passengers, regardless of weather conditions.
The ventilation and heating system includes: a heater, a heater fan, air ducts and deflectors.
Through the air ducts, the air from the heater is supplied to the windshield and side window vents, to the central and side vents on the instrument panel, as well as to the ventilation openings in the heater casing to supply air to the feet of the driver and passengers.
The system is controlled by turning the handles located on the ventilation, heating and air conditioning control unit.
The control unit is installed on the instrument panel console.
The heater is installed under the instrument panel on the right, air ducts are fixed under the instrument panel.
The heater housing contains a heater fan, an additional heater fan resistor, distribution dampers that direct air flows to certain areas, and a heater radiator connected by hoses to the engine cooling system, through which coolant constantly circulates.
Depending on the position of the damper associated with the temperature controller, outside air can pass through the heater core or bypass it.
The air is heated by the heat of the engine coolant circulating through the tubes of the heater radiator.
For example, at an outside temperature of -18°C, the air after passing through the heater core heats up to 54°C, at -4°C - respectively, up to 59°C, at 10°C - up to 64°C.
When the car is moving, air enters the heater through grilles located in front of the windshield.
To increase the air supply to the passenger compartment while the car is moving, as well as in the parking lot, the heater fan is used.
The air supply intensity is determined by the fan speed.
Additional heater fan resistor
The fan motor, depending on the connection of an additional resistor, can rotate at four different speeds.
The distribution of air flows in the cabin is carried out by the air flow distribution regulator, which is connected by rods to the dampers.
By controlling the dampers, the regulator directs air flows through the air ducts to the central and side vents, to the lower ventilation openings in the heater casing, as well as to the windscreen grilles located in the instrument panel.
Air outlet valves
Air exits the passenger compartment through openings located on top of the sides of the trunk, and then out through valves installed behind the sides of the rear bumper.
To accelerate the warm-up of the passenger compartment and prevent the entry of outside air into the passenger compartment (when driving on smoky, dusty sections of the road) is an air recirculation system.
When the lever for switching on the air recirculation mode is moved, the damper of the recirculation system blocks the access of outside air to the car interior, while the air in the car interior begins to circulate in a closed circuit without exchange with outside air.
Some cars are equipped with an air conditioning system.
The air conditioning system is designed to reduce the temperature and humidity in the cabin.
The air conditioner is turned on by pressing the air conditioner switch button located in the heating, ventilation and air conditioning control unit, while the heater fan must be turned on.
When the air conditioner is turned on, the warning lamp next to the air conditioner switch button lights up.
The air conditioning compressor is mounted on the engine bracket in front, on the right.
The compressor is driven by a V-belt from the accessory drive pulley.
An electromagnetic clutch is built into the compressor pulley, which turns the compressor shaft on and off from the pulley according to ECU signals.
After the compressor, the refrigerant vapor enters the condenser, located in front of the radiator of the engine cooling system.
Next, the refrigerant enters the receiver, which is mounted on the condenser, on the right side.
From the receiver, the refrigerant enters the gearbox, and then to the evaporator, located under the instrument panel in the heater housing.
The air thus cooled enters the passenger compartment.
From the evaporator, the refrigerant is again sucked in by the compressor, and the working cycle is repeated.
The high and low pressure pipelines are equipped with valves for charging and discharging refrigerant from the air conditioning system.
A refrigerant pressure sensor is installed on the pipeline between the compressor and the condenser.
The pressure sensor sends a signal to the ECU, which controls the electric fans of the engine cooling system, depending on the amount of refrigerant pressure and vehicle speed.
In addition, according to the pressure sensor signals, the ECU turns off the air conditioning compressor when the refrigerant pressure in the system drops to 2.0 bar and when the pressure rises to 27.0 bar.
A shut-off valve is installed in the pipeline fitting, under the pressure sensor, which closes when the sensor is unscrewed.
Therefore, when replacing the pressure sensor, refrigerant leakage from the air conditioning system will not occur.
The refrigerant in the air conditioning system is under high pressure.
During work related to the depressurization of the air conditioning system, contact with eyes, skin and respiratory tract should be avoided.
Any work with refrigerant must be carried out only in a ventilated area.
When filling the air conditioning system, use only materials recommended by the manufacturer.
It is forbidden to carry out welding or soldering work on the components of the air conditioning system.
Work on the repair and maintenance of the air conditioning system should be carried out at specialized services.
To search for leaks in the system, special equipment is used, while a special contrast agent will need to be injected into the system.
After removing the refrigerant from the system, be sure to pump out air to remove residual moisture.
Before filling the system, it is necessary to add special oil recommended by the manufacturer.