Does the fan in engines always turn when car is on?

In most modern cars, the engine fan is controlled by a thermostat and only turns on when the engine reaches a certain temperature. This is done to improve fuel efficiency and reduce noise. However, some older cars may have fans that run continuously, regardless of engine temperature.

When the engine is cold, the fan is turned off to allow the engine to warm up more quickly. As the engine warms up, the thermostat opens and allows coolant to flow through the radiator. The fan is then turned on to help dissipate heat from the radiator and keep the engine from overheating.

The fan is usually powered by an electric motor, which is controlled by a relay. The relay is activated by the thermostat, which is a temperature-sensitive switch. When the engine reaches the desired temperature, the thermostat closes and the relay is activated, which turns on the fan.

The fan may also be turned on manually by the driver, using a switch on the dashboard. This can be useful in hot weather or if the engine is running hot.