Every liquid-cooled car engine comes with a small device called thermostat. The automotive thermostat sits between the engine and the radiator having a function to block coolant flow towards the radiator till the time engine does not get warm. In most of the vehicles, it comes with a size of around 2 inches in diameter. When an engine is cold, the coolant does not flow and time it reaches the required temperature which is around 200-degree Fahrenheit, the car thermostat opens. By allowing an engine to warm up quickly, it reduces the engine wear and emissions.
The thermostat power lies in a small cylinder placed on the engine-side of it. This small cylinder is filled with wax which starts to melt at a temperature of 180-degrees F. The valve connected rod presses the wax. And when the cylinder wax melts, it expands noticeably and pushes the rod out from the cylinder, opening the valves. It is important for proper functioning of car ac.