Description of systems
The description of the control of the ventilation system with a heater and K / V is given in the Chapter Controls and methods of operation.
The coolant heated in the engine is passed through a heat exchanger, giving off heat to the air passing through it. The air supply to the cabin is controlled by dampers. If you turn on the heater fan, the air will be supplied to the passenger compartment more intensively. The fan speed can be adjusted. When the damper is closed, the coolant flows through a small circuit back into the engine radiator circuit.
Before getting into the cabin, the air passes through a filter, in which the bulk of the dust settles. The filter replacement interval must be observed, as a filter blocked by dust restricts the air supply, which will lead to stagnation of air inside the passenger compartment.
The distribution of air flows of the ventilation system is also carried out with the help of dampers. On all models the mode of air circulation is provided.
System air conditioning (K/V) installed as optional equipment.
Work on the A/C system must be carried out in a specialized workshop. Do not open the refrigerant circuit, as the refrigerant may cause frostbite if it comes into contact with the skin.
With the help of the K / V system, the air temperature in the cabin can be lowered relative to the outside temperature. In addition, when the K / V system is operating, the humidity in the cabin decreases.
Refrigerant circulates in the system R134a, which, depending on temperature and pressure, can be in a liquid or gaseous state. A schematic description of the refrigerant flows is shown in the illustration below.
Functional diagram of the A/C system
1 - Fan; 2 - Evaporator; 3 - Expansion valve; 4 - Dryer; 5 - Condenser fan; 6 - Capacitor; 7 - Compressor; a - Outside air; b - Heated air; c - Warm outside air; d - Cooled outside air; A - High pressure circuit, gaseous refrigerant; B - High pressure circuit, liquid refrigerant; C - Low pressure circuit, liquid refrigerant; D - Low pressure circuit, gaseous refrigerant
The A/C compressor is belt driven from the engine crankshaft and pressurizes the gas refrigerant circuit. This heats up the refrigerant. In the condenser, the refrigerant is cooled by outside air. As a result, the heated refrigerant passes into the liquid phase. The high-pressure refrigerant is then passed through the expansion valve, causing the refrigerant pressure to drop. After that, the refrigerant evaporates in the circuit, while being strongly cooled. In the evaporator, the refrigerant removes heat from the air blown through it. As a result, the air is cooled and enters the interior of the car. As a result of heating in the evaporator, the refrigerant turns into a gas and enters the compressor under low pressure, after which the circulation process is repeated.
To maintain normal pressure in the A/C system, a refrigerant pressure sensor is designed to turn off the compressor if the pressure exceeds 27.9 atm or getting lower 1.4 atm.
Location of A/C system components
Additional information about the K / V system is indicated on the nameplate attached to the hood.
To lubricate the components of the A/C system, compressor oil is used, which circulates in the system along with the refrigerant. After replacing any component of the A / C system, as well as when a leak is detected, oil should be added to the system (see Section Refrigerant Level Correction).
Some of the vehicles in question may be equipped with an automatic heating, ventilation and air conditioning system. This system is described in Chapter Controls and methods of operation.
Security measures for servicing the A/C system
Maintenance of the A/C system should be entrusted exclusively to trained technical personnel who are trained in safe work practices using proper equipment and in compliance with depressurization rules, as well as familiar with the methods of collecting and storing automotive refrigerant.
- Avoid skin contact with refrigerant;
- When working near the A/C system, wear protective goggles;
- If refrigerant comes into contact with skin or eyes, do not rub the affected area. Immediately flush the affected area with cold water for at least 15 minutes and seek qualified medical attention. Self-medication is not allowed;
- The refrigerant is stored in pressurized cylinders. Store the cylinder at a temperature not exceeding 50 degrees. Take measures to prevent the cylinder from falling from a height or other situations that may lead to its damage;
- Work should be carried out in a well-ventilated area. The refrigerant evaporates quickly, leading to a decrease in oxygen access and difficulty breathing;
- The gaseous refrigerant is heavier than air and must collect relatively quickly at the bottom, for example, under a car;
- When the refrigerant burns, poisonous gas is produced. Keep refrigerant away from open flames. Do not smoke when working with the A/C system;
- When carrying out welding work near the A/C system, do not expose it to high temperatures or open flames. Overheating can lead to an increase in pressure in the system and ignition;
- Cleaning the condenser or evaporator with steam is not permitted. Use only cold water or compressed air.