Engine cooling system
All models of vehicles considered in this Manual are equipped with an engine cooling system operating under excess pressure with thermostatic control of the circulation of the working fluid (see illustrations below). The rotary water pump is mounted on the engine block and pumps coolant through the latter. The flow of liquid washes the areas of each cylinder in the block and is directed to the rear of the engine. Cooling channels laid in the block and cylinder head casting provide intensive cooling of the intake and exhaust ports, spark plug installation areas and exhaust valve guides.
A wax-filled thermostat controls the engine operating temperature during its warm-up. In the first minutes after starting a cold engine, the thermostat remains closed, thereby preventing the coolant from circulating through the radiator. When the engine temperature reaches the normal operating value, the thermostat valve opens, connecting the radiator to the cooling circuit, ensuring maximum intensity of heat removal from the working fluid (coolant).
The cooling system is closed by a hermetically sealed radiator cap capable of withstanding a certain excess pressure, which increases 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 the flow of excess coolant through the connecting (overflow) tube into the expansion tank. As the system cools, the liquid from the tank automatically returns to the radiator.
Adding coolant to the system is done through the neck of the expansion tank, which also acts as a receiver, accumulating excess liquid displaced from the radiator.
Due to the listed design features, such a cooling system is called closed, since it eliminates any functional losses 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 heater casing. The heat exchanger is connected to the engine cooling system via rubber hoses. The heater/air conditioner control unit is mounted in the vehicle's instrument panel. 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 plate damper opens and the internal volume of the heater casing is connected to the volume of the interior. When the fan is turned on, the impeller of the latter begins to drive the air entering the interior through the heat exchanger, ensuring its 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-dryer equipped with a pressure-reducing valve. All components are connected to each other by refrigeration lines.
The fan drives the air entering the cabin through the evaporator heat exchanger, which operates in the opposite mode to the radiator. The refrigerant pumped through the heat exchanger evaporates, taking excess heat from the air. The temperature inside the cabin is reduced to a comfortable value (at the operator's choice).