* Thermostatically Controlled: The fan is controlled by a sensor in the cooling system. When the coolant temperature reaches a certain point (usually around 220-230°F), the sensor signals a relay to energize the fan motor. Once the coolant cools down sufficiently, the fan turns off. This is the most common mode of operation.
* A/C Controlled: When the air conditioning is running, the fan will often come on regardless of coolant temperature. This is to help dissipate heat from the A/C condenser, which is located in front of the radiator. The A/C system's pressure switch or other sensor signals the fan to run.
In short: The fan's job is to keep the engine from overheating. It usually runs only when needed, either due to high coolant temperature or A/C operation. Sometimes, both systems may activate the fan simultaneously.
If your fan isn't working correctly, there are several potential issues: a faulty fan motor, a bad relay, a malfunctioning temperature sensor, problems with the A/C system, or wiring issues. A mechanic can diagnose the specific problem.
