How to Deal with a Constantly Running Radiator Fan?

[DeAddyson]

Ways to handle a constantly running radiator fan: First, check if the radiator is low on coolant. Additionally, check whether the air conditioning is set to forced cooling mode. If neither of these is the issue, then inspect whether the coolant temperature sensor is functioning properly. If the temperature sensor is faulty, it needs to be replaced. When the engine coolant temperature is high, the water pump circulates coolant repeatedly to lower the engine temperature, thereby protecting the engine. If the fan continues to run after the engine is turned off, it indicates that the coolant temperature has not yet dropped, and the engine remains in a high-temperature state. The wiring for the coolant temperature sensor is not controlled by the ignition system. As long as the temperature remains high, the sensor will send a high-temperature signal to the engine control unit (ECU), causing the fan to keep running to cool the engine until the temperature drops to an appropriate level and the fan stops.

[LilyMarie]

Last time I encountered the radiator fan running continuously was after a long drive—it kept buzzing even after parking. Upon inspection, I found the coolant level was slightly low, likely due to neglecting regular maintenance. Adding some proper antifreeze mixture improved the situation. If the fan keeps running, it’s often due to a faulty temperature sensor or a blockage in the cooling system, tricking the fan into thinking the engine is still hot. It’s advisable to regularly check if the engine temperature gauge reads normal and replace the coolant if it appears cloudy. Before DIY repairs, ensure the engine is off and cooled down safely, avoiding direct contact with hot components. Delaying repairs can drain the battery, making nighttime starts troublesome—prompt action saves hassle and money.

[DelMadeline]

The constantly running radiator fan is quite annoying. Start with basic troubleshooting steps. Open the hood and check if the coolant reservoir level is below the minimum line. If low, add a 50/50 mixture of distilled water and antifreeze. Then inspect whether the fan fuse is blown; its location is marked as COOLING FAN in the fuse box. Use a multimeter to measure the voltage at the fan connector. If abnormally high, it might indicate a control module failure. Also, clean any oxidized related circuit connectors to ensure secure connections. Prolonged abnormal fan operation drains the battery quickly, affecting starting performance. Fix it as soon as possible for safer driving.

[VanDelilah]

I'm a bit worried that the radiator fan running continuously might cause engine overheating and damage, especially during summer traffic jams when it's more dangerous. This is usually caused by false alarms from the low coolant level sensor. If the fan keeps running after the engine has cooled down when parked, it should be addressed. Just check that the coolant reservoir level is within the normal range and not too low, and avoid adding tap water randomly to prevent rust. Low battery voltage can also trigger incorrect fan operation. It's best to get the electrical system checked at a professional shop as early as possible—safety first.