What are the common faults of cooling fans?

1、 Rotation related faults (most common) Fan not turning: It may be due to power interruption, motor burnout, bearing jamming (dust/oil solidification), or damaged starting capacitor (AC fan). Rotation stuttering/abnormal noise: mostly caused by bearing wear, excessive dust accumulation on the fan blades, or friction between the fan blades and the casing/cables. Speed fluctuates rapidly: DC fans may have abnormal PWM speed control signals, while AC fans may have unstable voltage or aging capacitors. 2、 Performance degradation fault The air volume has significantly decreased: dust accumulation on the fan blades blocking the air duct, increased bearing resistance leading to a decrease in speed, or deformation of the fan blades. Poor heat dissipation effect: Even if the fan is running, the heat exchange efficiency may decrease due to air duct blockage or excessive installation clearance (air leakage). 3、 Electrical and safety faults Power on tripping/short circuit: The insulation layer of the motor coil is damaged, the wiring terminal is oxidized and short circuited, or the fan is exposed to water and moisture inside. Sudden increase in noise: severe bearing wear (ball bearings lack oil, oil containing bearings dry up), or loose or unbalanced fan blades. Severe fan heating: local short circuit in the coil, high power supply voltage, or long-term overload operation.