What Causes the Engine's Low-Speed Fan to Not Rotate?
2 Answers
Reasons why the engine's low-speed fan does not rotate: Relay malfunction: If the coolant temperature meets the requirements but the car's radiator fan still does not operate, the issue could lie with the fan's relay. A faulty relay can prevent the radiator fan from functioning. Coolant temperature not reaching the threshold: Modern car radiator fans typically operate using electronic temperature control. Therefore, the fan will only start rotating normally when the engine's coolant temperature reaches the required level. Thermostat switch failure: If neither of the above issues is present, the thermostat switch should be inspected. This component can sometimes develop faults, which may affect the operation of the car's radiator fan. Hence, it is important to check this as well.
After all these years as a mechanic, I've encountered countless cases of low-speed fan failures. There are several common causes that need to be checked one by one. It could be a faulty temperature sensor failing to send signals when the fan should activate; or a seized/burnt-out fan motor due to aging causing rotation issues; poor relay contact failing to control the circuit; blown fuse cutting off current; short circuits, broken wires, or corroded/loose connectors may also be factors. During inspection, start the vehicle and observe the fan status after engine warms up. Simple checks like replacing fuses in the fuse box might help. If still not working, professional equipment is needed to test sensor voltage and motor resistance. Non-functioning cooling fans are extremely dangerous as they can cause engine overheating and cylinder seizure, leading to costly repairs. Regular maintenance like radiator cleaning and proper coolant replenishment can prevent many such issues.
