When Does the Car Fan Turn On?
2 Answers
The radiator fan in a car operates based on the coolant temperature, typically activating when the temperature reaches around 80-90 degrees Celsius. The reasons why a car radiator fan may not turn on are as follows: 1. Whether the coolant temperature meets the requirement: With the continuous advancement of automobiles, many car radiator fans now operate electronically based on temperature control. During driving, the radiator fan will only turn on when the coolant reaches the required temperature. If the coolant temperature in the radiator does not meet the requirement, the fan will not operate, indicating that the fan is not faulty but that the coolant temperature needs to be checked. 2. Relay failure: If inspection shows that the coolant temperature has reached the threshold for the fan to operate, but the engine's radiator fan still does not work, it may be due to a faulty relay. A malfunctioning relay cannot transmit signals, preventing the radiator fan from operating. 3. Thermostat switch issue: If all the above components are confirmed to be functioning properly, the thermostat switch should be inspected. A faulty thermostat switch can also disrupt the normal operation of the radiator fan.
The fan in a car typically starts running under three circumstances. When the engine temperature rises, such as during traffic jams or hot weather, the coolant temperature sensor detects the high temperature and automatically activates the fan to cool down the engine, preventing overheating damage—this is a protective mechanism. When the air conditioning is turned on, the fan also runs to assist the radiator in cooling the refrigerant; otherwise, the AC performance would deteriorate. Additionally, there are specific conditions set by the fan control module, such as activating the fan when the temperature reaches a certain level after a cold start or running the fan for a while after parking and turning off the engine to dissipate residual heat. I’ve seen many cases where sudden fan failure led to overheating and breakdowns, so it’s crucial to inspect the fan circuit and sensors during regular maintenance to prevent minor issues from escalating into major failures. Over time, drivers should learn to listen to the fan’s sound to judge whether it’s functioning properly—this can save a lot on repair costs.
