Toyota RAV4>> Cooling systems and conditioning>> General information>> Cooling system
The engine of the car is operated in various climatic conditions and at various loadings. At the same time temperature of cooling liquid has to remain in the narrow temperature range that is provided by the engine cooling system.
The cooling system the closed liquid, turns on the water pump with the drive an auxiliary belt from a bent shaft, the radiator fan with the electric drive, a radiator, a broad tank, the thermostat , a heater radiator, hoses and switches.
The water pump of bladed type is installed in front on the block of cylinders.
The thermostat depending on temperature of cooling liquid automatically includes or disconnects a cooling system radiator, passing liquid through a radiator or passing it.
At launch of the cold engine cooling liquid does not come to a radiator as the main valve of the thermostat is closed, and perepuskny is open. Cooling liquid circulates on a shirt of the block and a head of the block of cylinders, then again comes to the pump. Bystry warming up of the cold engine is so provided.
When cooling liquid reaches temperature of opening of the thermostat, the firm wax filler of the thermostat extends, squeezes a rubber insert and pushes out the piston. At the same time the main valve will open completely, and perepuskny will completely be closed. Hot cooling liquid passes through a hose to a radiator and is cooled with a stream of counter air.
The fan of a radiator turns on a thermoswitch depending on temperature of cooling liquid.
The radiator of cooling is closed by a tight cover. The cover creates elevated pressure in the cooling system that lifts temperature of boiling of cooling liquid, and more high temperature of boiling of cooling liquid increases efficiency of a radiator. If pressure in system exceeds a preset value, the safety valve in a cover opens and produces cooling liquid through a hose in a broad tank. When cooling cooling liquid flows from a tank back in a radiator.
The broad tank performs two functions: serves as capacity for collecting heated cooling liquid and for replenishment of the cooling system.
The air given by system of ventilation to interior of the car can be warmed up or cooled, depending on the conditions of comfort chosen by the driver and passengers. Systems of heating and conditioning separate, however their units and knots are located in interior of the car in the general case under the dashboard. All stream of the air given to salon goes for heating or cooling through the same air ducts. Temperature and speed of a stream of air is regulated by means of the same governing bodies.
Heat generated during the operation of the engine is transferred by cooling liquid to the heater radiator located in salon. The air stream from the fan of salon passes through a radiator and heats up heat of cooling liquid.
If the air which is coming out ventilating grates does not heat up, the following reasons are possible:
the thermostat is constantly open therefore cooling liquid does not heat up to the required temperature and does not transfer enough heat to a heater radiator. In this case replace the thermostat ;
– hoses of supply of cooling liquid to a heater radiator are littered. Check temperature of hoses about a partition of a motor compartment, they have to be hot. If one of hoses cold, so is available a contamination of hoses or a radiator of a heater. Disconnect hoses from unions on a partition of a motor compartment and, in turn pumping water under pressure in unions, wash out hoses and a radiator of a heater;
– if washing of a radiator of a heater did not yield positive results, replace a radiator.
Cooling liquid

       PREVENTION
Do not allow hit of cooling liquid on clothes and a paint and varnish covering of a body. Otherwise wash out a surface a large amount of water.
Collect and utilize the merged cooling liquid.

The cooling system has to be all the year round filled with cooling liquid. Cooling liquid represents mix of etilenglikolevy antifreeze and the distilled water in the ratio 50:50. In zones with a frigid climate the content of antifreeze in cooling liquid can be increased according to recommendations of the producer of liquid, however should not exceed 70%.
Optimum concentration of antifreeze excludes freezing of liquid in the block of cylinders of the engine, formation of corrosion and a limy deposit, and also increases temperature of boiling of cooling liquid.
Replacement of cooling liquid with washing of the cooling system needs to be made every two years. Before filling of the cooling system check a condition of hoses and their fastenings. In use the car the level of cooling liquid should not change. Bystry falling of level of cooling liquid indicates a leak and need of its elimination. Check a condition of a radiator, the water pump, hoses, connections and traffic jams of discharge for existence of dribble traces on them. If leaks are not found, check for service stations pressure of opening of the valve in a radiator cover.
Replacement of cooling liquid needs to be made also after carrying out any works on cooling system elements with discharge of cooling liquid. If at repair the head of the block of cylinders, laying of a head of the block, a radiator or the heat exchanger of oil were replaced, fill in fresh cooling liquid in the cooling system. It is connected with the fact that anticorrosive additive in cooling liquid during the operation of the engine is besieged and creates anticorrosive protection. In the cooling liquid which was in operation, anticorrosive additives are insufficiently active to form a protective layer on again established details.