Engine cooling system
All vehicles covered in this manual use a sealed cooling system with coolant circulation controlled by a thermostat. A centrifugal water pump mounted at the front of the cylinder block pumps fluid through the engine. Coolant flows rearward around all cylinders. Internally molded cooling passages direct coolant around the intake and exhaust ports, to the spark plugs, and to the exhaust valve guides.
The solid-filled thermostat is mounted in a housing at the front of the engine. During engine warm-up, the closed thermostat prevents coolant from flowing through the radiator. Once the engine has warmed up to normal operating temperature, the thermostat opens and allows coolant to flow through the radiator, where it is cooled before returning to the engine.
The cooling system is hermetically sealed with a radiator cap. This increases the boiling point of the coolant, which in turn increases the efficiency of the radiator. If the pressure in the system exceeds the operating pressure of the relief valve, the valve opens and allows the liquid to be released through a tube into the tank. After the system has cooled, excess liquid is automatically drained from the tank back into the radiator.
The coolant reservoir serves a dual function - as a place to add additional coolant to maintain its level and as an expansion tank to drain overheated coolant.
This type of cooling system is known as a closed system because the fluid drained through the safety cap is reused.
Heating system
The heating system consists of a blower fan and a heater core located in the heater box, inlet and outlet hoses connect the heater core to the engine cooling system and the heating/air conditioning regulator on the instrument panel. Hot coolant circulates through the heater core. When the heating mode is turned on, the flaps open, opening the connection between the heater box and the passenger compartment. The fan switch on the regulator turns on the blower motor, which provides forced air flow through the radiator and heating.
Air conditioning system
The air conditioning system consists of a condenser mounted in front of the radiator, an evaporator mounted next to the heater core, a compressor mounted on the engine, a filter drier (accumulator) that contains a high-pressure relief valve, and pipes that connect all of the above components.
The blower fan forces air into the passenger compartment through the evaporator, transferring heat from the air to the refrigerant. The liquid refrigerant evaporates into low-pressure vapor, absorbs heat, and leaves the evaporator.