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http://autorepair.about.com/library/faqs/bl113g.htm
The cooling system is the radiator, engine fan, thermostat, and hoses...
The thermostat is located on the cooling system on a 2003 Toyota Corolla. The thermostat can also be found by following the upper radiator hose.
The cooling system thermostat can be located by looking down at the thick fat hose that comes out of the top of radiator. Visually follow this hose down to where it attaches by a clamp to a metal housing on the engine block. The cooling system thermostat is located within that housing.
The purpose of a thermostat cable in a heating and cooling system is to connect the thermostat to the heating and cooling equipment, allowing the thermostat to communicate with the system and control the temperature in the building.
The purpose of the thermostat R wire in a heating and cooling system is to provide power to the thermostat, allowing it to control the heating and cooling equipment in the system.
The purpose of an orange thermostat wire in a heating and cooling system is to connect the thermostat to the heating and cooling equipment, allowing the thermostat to control the temperature settings and activate the system as needed.
The purpose of the brown thermostat wire in a heating and cooling system is to connect the thermostat to the heating and cooling equipment, allowing the thermostat to control the temperature settings and activate the system as needed.
the thermostat is located in the housing where the top radiator hose enters the engine. Note: there is also a brass screw on the top of the housing, this is to bleed the air from the cooling system when you replace the thermostat (or do other cooling system repairs)
The function of a thermostat transformer in a heating and cooling system is to convert the standard voltage from the electrical system into a lower voltage that can be safely used by the thermostat to control the heating and cooling equipment.
The purpose of the thermostat power wire in a heating and cooling system is to provide electrical power to the thermostat, allowing it to control the temperature settings and activate the heating or cooling system as needed.
The thermostat in a 1996 VW Golf is located by following the lower large hose of the radiator. Before removing the thermostat be sure to drain the cooling system.
The cooling system thermostat can be located by looking down at the thick fat hose that comes out of the top of the radiator. Visually follow this hose down to where it attaches by a clamp to a metal housing on the engine block. After draining the cooling system - unclamp the hose and unbolt the housing from the engine block to access the thermostat.