How to determine if the malfunction of the cooling fan is caused by dust?

The core conclusion for determining whether the malfunction of the cooling fan is caused by dust is that it can be quickly locked through three steps: "appearance observation+operation status verification+post cleaning testing". Dust induced faults are often accompanied by the characteristics of "visible dust accumulation+significant symptom relief after cleaning".
1、 Visual judgment of appearance
Observing the fan blades and casing: There is obvious dust accumulation on the surface of the fan blades, around the shaft, or at the fan inlet/outlet, even forming flocculent dirt, which may block the air duct or jam the shaft.
Check gaps and filters: Fans with filters (such as computer case fans) have clogged filters due to dust, resulting in poor air intake; There are dust clumps at the gap between the fan and the device casing, which affect the airflow.
2、 Auxiliary judgment of operating status
Fan not turning/lagging: After power on, the fan does not respond, and there is resistance when manually pulling the fan blades (when there is no foreign object entanglement). It is most likely that dust mixed with oil has solidified at the bearing, hindering rotation.
Reduced air volume+abnormal noise: The fan can rotate but the air output is weak, accompanied by a "buzzing" muffled sound or slight friction sound, mostly due to dust adhering to the fan blades, increasing weight, disrupting dynamic balance, or blocking the air duct, resulting in airflow obstruction.
Unstable speed but normal power supply: After eliminating voltage and speed control signal issues, the speed fluctuates rapidly, possibly due to uneven bearing resistance caused by dust and motor load fluctuations.
3、 Verification after cleaning (key steps)
Simple cleaning: Use a brush to remove visible dust from the fan blades, shaft, and air duct, and use a hair dryer to blow away dirt in the gaps (to avoid damage to the motor from hot air).
Test comparison: After cleaning and powering on, if the previous symptoms such as "no rotation, lagging, low air volume, and loud noise" have significantly improved or completely disappeared, it can be confirmed that the fault is caused by dust; If there is no change in symptoms, it is highly likely that there are other issues such as bearing wear, motor failure, etc.