What are the reasons for a car's cooling fan not having a low speed?
4 Answers
There are several reasons why a car's cooling fan may not have a low speed, including the operation of the electric fan, the opening of the thermostat, and the phenomenon of water pump cavitation. Below are the relevant explanations: 1. Whether the electric fan is working properly: Normally, the electric fan has two speeds. One is the low speed, and the other is the high speed. The high speed usually operates when the air conditioning pressure is too high or when the engine's coolant temperature reaches 103 degrees Celsius. 2. Whether the thermostat's opening is insufficient: If the thermostat's opening is too small at normal temperatures, it will slow down the circulation speed of the engine's coolant. This can lead to high coolant temperatures at low speeds. 3. Check if the water pump is experiencing cavitation: The water pump impeller is made of plastic. If the shaft part cracks, it can cause cavitation when the coolant temperature is high, leading to elevated coolant temperatures.
I remember once my car's cooling fan suddenly stopped working at low speed, causing the engine to overheat. After checking, possible causes included burnt fan motor coils leading to low-speed failure, or aged wiring causing short circuits or open circuits. Blown fuses are also a common issue, especially when excessive current interrupts the low-speed circuit. If the control module malfunctions, such as a failed temperature sensor, the fan won't receive low-speed signals. I recommend starting with simple checks - inspect the fuse box and fan connectors for looseness. Always monitor the temperature gauge while driving, as fan malfunctions can easily damage the engine and increase repair costs. It's best to have professionals test the cooling system during regular maintenance to avoid roadside breakdowns.
The cooling fan has no low speed, and there may be several typical faults. The most common is relay damage, where the contacts are burned and cannot switch to the low-speed gear. There could also be internal issues with the fan motor, such as a broken low-speed coil or it being stuck. Poor or damaged wiring, especially in older cars where oxidation is severe, can also cause this. If the temperature sensor is inaccurate or the control module fails, the fan may run only at high speed or stop completely. I've encountered many such cases while repairing cars, and it's important to fix them promptly; otherwise, uncontrolled engine temperature can shorten its lifespan. Keeping the fan clean is essential, as excessive dust can reduce cooling efficiency. Using a multimeter to check the circuit is a basic method—only by identifying and eliminating the root cause can you be at ease.
My friend's car has an issue where the cooling fan doesn't operate at low speed. After checking online, common causes include fan motor failure, wiring short circuits, or relay problems. A faulty control box can also cause the fan to only run at high speed, and sensor misjudgment may be another culprit. Timely inspection can prevent engine overheating and boiling. During daily driving, pay attention to the fan's noise; if it sounds abnormal, pull over to check, which can save you from expensive engine repairs.
