If your car has an automatic transmission, the fan clutch is a key component to keeping your engine cool. The fan clutch is what allows the fan to spin faster or slower, depending on the needs of the engine. If the clutch is not working properly, it can cause the engine to overheat.
The fan clutch is engage when the engine is started and disengages when the engine reaches operating temperature. When it first engages, you may notice that the fan sounds like it is straining or working harder than normal. This is because the cold oil in the system makes it harder for the fan to turn. As the oil warms up, it becomes thinner and easier for the fan to turn.
You should be able to turn your car's clutch by hand with moderate effort when it is cold. If it takes a lot of effort to turn or if you can't turn it at all, there could be an issue with your car's cooling system. Try checking your radiator fluid levels and making sure there are no leaks in your system before taking your car to a mechanic.