Engine cooling system
All vehicle models covered in this manual have a closed, pressurized cooling system with two thermostatically controlled coolant circuits (pic. 1.1). To ensure fluid circulation, a centrifugal-type water pump is installed on the cylinder block. Coolant circulates around each cylinder from the front to the rear of the engine. Channels circulate fluid around each valve, around the spark plug holes, and around the exhaust valve bushings.
Wax filled thermostat (pic. 1.2). located at the rear of the engine on the side of the transmission mount. When the engine warms up, the thermostat is closed and no fluid enters the radiator. When the operating temperature is reached, the thermostat opens and the coolant begins to circulate through the radiator, where it is cooled. The cooling system operates under pressure, which is regulated by an exhaust valve in the radiator cap. Excessive pressure in the cooling system raises the boiling point of the liquid, and also increases the efficiency of the radiator. If the pressure in the system exceeds the allowable value, the valve in the radiator cap opens slightly, and excess coolant enters the expansion tank. As the engine cools, the coolant is automatically drawn back into the radiator.
The expansion tank serves to replenish the cooling system with fresh liquid and to store the excess liquid formed during the volumetric expansion of the heated coolant.
This type of cooling system is known as a closed system because excess coolant flows into the expansion tank (and back) and is used repeatedly.
Heating system
The heating system consists of a fan, a heater radiator located under the front panel on the right side, hoses connecting the heater radiator to the engine cooling system, as well as heater / air conditioning control knobs located on the front panel. The coolant of the engine cooling system circulates through the heater core. When the heating system is turned on, the damper opens and the fan turns on. The air flow created by the fan passes through the heater core and warm air begins to flow into the car interior.
Air conditioning system
The air conditioning system consists of a condenser located in front of the radiator, an evaporator mounted next to the heater radiator, a compressor mounted on the engine, a filter drier containing an overpressure relief valve, and piping connecting all of the above-mentioned components.
The heater blower blows warm air from the vehicle interior to the evaporator grille. In the evaporator, the air gives up its heat to the refrigerant, causing the air to cool, and the liquid refrigerant to boil, turning into low-pressure vapor. The compressor circulates the refrigerant and pumps the heated refrigerant from the evaporator through the condenser. The refrigerant cools down in the condenser and re-enters the evaporator.
Until 1994, the air conditioning system was charged with A-12 refrigerant. Since 1994, the system has been charged with the more environmentally friendly R-134a refrigerant. These refrigerants are not compatible, just as the oils used in the systems are not compatible. Even after refrigerant A-12 is released from the system, its residues still remain in the cavities and hoses of the system, so simply filling the system with R-134a refrigerant can only have a negative effect. In no case should this be done in a garage without special equipment and experience. In addition, systems designed for different types of refrigerants differ structurally and their parts are also not interchangeable.