Engine cooling system
All models of vehicles discussed in this manual are equipped with a positive pressure engine cooling system with thermostatically controlled circulation of the working fluid (see illustrations below). The rotary type water pump is mounted on the engine block and provides coolant pumping through the latter. The flow of fluid washes the areas where each of the cylinders in the block is located and is directed to the rear of the engine. Cast-in-the-block and cylinder-head cooling ducts provide intensive cooling for intake and exhaust ports, spark plug areas and exhaust valve guides.
The wax-filled thermostat controls the operating temperature of the engine during engine warm-up. In the first minutes after starting a cold engine, the thermostat remains closed, thereby preventing the circulation of coolant through the radiator. When the engine temperature reaches normal operating temperature, the thermostat valve opens, connecting a radiator to the cooling circuit, ensuring maximum heat removal from the working fluid (coolant).
The cooling system is closed with a sealed radiator cap capable of withstanding a certain excess pressure, which ensures an increase in the boiling point of the coolant and, accordingly, the efficiency of heat removal through the radiator. When the internal pressure in the system exceeds a certain value, the spring-loaded plate of the safety valve mounted in the radiator cap rises above its seat, ensuring that excess coolant flows through the connecting (overflow) tube into the expansion tank. As the system cools down, the fluid from the tank automatically returns to the radiator.
Coolant is added to the system through the neck of the expansion tank, which also acts as a receiver, accumulating the excess liquid displaced from the radiator.
In view of the listed features of its design, such a cooling system is called closed, since it excludes any functional loss of coolant.
Heating system
The main components of the interior heating system are an electric fan and a heat exchanger located in the box-shaped casing of the heater. The heat exchanger is connected to the engine cooling system via rubber hoses. The control unit for the functioning of the heater / air conditioner is mounted in the instrument panel of the car. The coolant heated in the engine circulates through the heater heat exchanger, giving off its heat to the air contained in the casing. When the interior heating is turned on, the leaf damper opens and the internal volume of the heater casing is connected to the interior volume. When the fan is turned on, the impeller of the latter begins to drive the air entering the passenger compartment through the heat exchanger, providing it with intensive heating.
Air conditioning system
The system consists of a condenser installed in front of the radiator, an evaporator located next to the heater heat exchanger, a compressor mounted on the engine block and a receiver-drier equipped with a pressure reducing valve. All components are interconnected by refrigeration lines.
The fan drives the air entering the passenger compartment through the evaporator heat exchanger, which operates in the reverse mode of the radiator. The refrigerant pumped through the heat exchanger, evaporating, takes away excess heat from the air. The temperature inside the cabin at the same time reduces to a comfortable value (operator's choice).