What are the factors that cause the cooling fan to slow down?-Capital-Cooling fan manufacturer

1、Blockage by dust and debris
After long-term use, the fan blades, bearings, or heat dissipation holes will accumulate dust, hair, fibers, and other debris, which increases the resistance to the rotation of the fan blades and leads to a decrease in speed.

In severe cases, it may even jam the fan blades, resulting in "locked-rotor" (complete inability to rotate).

2、Wear or aging of bearings
Fan bearings (such as ball bearings and oil-impregnated bearings) are core rotating components:

For oil-impregnated bearings, after long-term use, the lubricating oil will volatilize or dry up, increasing friction, reducing speed, and possibly accompanied by increased noise.

If ball bearings are worn or internal steel balls are damaged, rotation will become unsmooth, and the speed will slow down.

3、Deformation or damage of fan blades
Fan blades may deform due to external impact, high-temperature baking, or aging, destroying the dynamic balance and generating additional resistance during rotation, leading to a decrease in speed. Fractured or missing fan blades will also directly affect rotation efficiency.

4、Installation issues
If the fan is installed too tightly (such as skewed screws or deformed brackets), it may compress the fan body, restrict the rotation space, and cause the speed to slow down. An inclined installation position, where the fan blades rub against surrounding components (such as heat sinks), will also increase resistance.

二、Factors related to electrical and circuit systems

1、Insufficient supply voltage/current
Fan speed is directly related to the supply voltage (most DC fans have voltage ranges such as 5V, 12V, etc.):

If the power adapter is faulty or the line contact is poor (such as loose plugs, aging wires), the actual input voltage will be lower than the rated value, resulting in a speed drop.

Damage to components such as resistors and capacitors in the circuit (e.g., increased resistance, reduced capacitor capacity) will also reduce the voltage/current output to the fan.

2、Drive circuit failure
Damage to the fan's driver chip (such as a PWM controller) or speed control circuit may prevent it from outputting normal control signals, causing the speed to be locked in a low gear. For example, a PWM speed-regulating fan with a faulty controller may fail to receive or parse speed control signals, maintaining the minimum speed.

3、Problems with motor coils
Aging, short circuits, or open circuits in the internal coils of the motor will reduce motor efficiency, resulting in insufficient output power and lower speed. Moisture or corrosion of the coils (e.g., in a humid environment) may also affect conductivity, indirectly causing the speed to slow down.

三、 Factors related to environment and usage conditions

1、Impact of high-temperature environment
Long-term use in high-temperature environments (such as inside a chassis in summer, near industrial equipment) will accelerate the aging of fan components:

Plastic fan blades may soften and deform due to high temperatures, increasing resistance.

The volatilization rate of bearing lubricating oil accelerates at high temperatures, leading to insufficient lubrication.

The insulation layer of motor coils ages, reducing conductivity.

2、Low-temperature or humid environment
In low-temperature environments, the lubricating oil in oil-impregnated bearings may solidify, increasing friction; humid environments may cause rust on metal parts, hindering rotation.

四、Factors related to control logic and software

1、Abnormal speed regulation function
Smart fans (such as computer CPU fans, cooling bases) usually control speed through temperature sensors and software:

If the temperature sensor is faulty (falsely reporting low temperature), the software will mistakenly think that high-speed heat dissipation is unnecessary and automatically reduce the fan speed.

Incorrect settings in the motherboard BIOS, driver programs, or control software (such as locking in low-speed mode) may also cause abnormal speed.

2、Load matching issues
Some fans need to match specific loads (such as the air pressure requirements of heat sinks). If the replaced fan's air pressure/air volume does not match the load, it may be forced to slow down due to "overload" (common in industrial cooling systems).

Summary

The slowdown of cooling fan speed is the result of the combined effect of multiple factors, with mechanical wear, dust blockage, abnormal power supply, and circuit faults being the most common causes. In daily use, regularly cleaning dust, checking power supply lines, and maintaining bearing lubrication can effectively reduce the problem of speed reduction. For circuit or motor faults, professional testing and component replacement are required.

Capital Technology Co., Limited is the chief agent of SANYO DENKI, one of the leading enterprises of the cooling fan industry. We are a factory who also have our own independent brand CAPITAL product series. The main products are cooling fan, DC/AC fan, radiator, filter, reactor etc. We can provide customer with the most professional and perfect technical support, welcome to contact me at anytime at rainlee@szcpt.com.

Previous: What methods can be used to increase the rotational speed of a cooling fan when the voltage is insufficient?

Next: Is a higher protection level of cooling fans always better?

新闻中心

Sorry，当前栏目暂无内容!

Sorry，The current column has no content!