The decrease in cooling fan speed is typically caused by several common issues. Understanding these causes can help us identify problems early and address them, ensuring the fan operates efficiently over time.

1. Capacitor Failure
   The capacitor plays a vital role in the fan motor, helping it start and maintain a stable speed. If the capacitor fails, the fan's speed may decrease or it may not function properly. Over time, especially in high-temperature environments, the capacitor's capacity diminishes.
   Solution:
   Use a digital multimeter to test the capacitor for damage. If it's faulty, replace it. For improved performance, consider choosing a capacitor with 20% more capacity than the original to enhance startup and stability.

2. Insufficient Motor Lubrication
   The lubrication of the motor directly impacts its efficiency. Insufficient lubrication increases friction, which can reduce the fan's speed and even cause the motor to struggle. This typically occurs when the motor bearings lack lubrication or the lubricant has dried up.
   Solution:
   After turning off the power, manually spin the fan blades to check for abnormal friction. If resistance is high, the lubrication is likely insufficient. Add appropriate lubricating oil to the motor bearings. Regular maintenance and lubrication are key to prolonging the fan's lifespan.

3. Motor Short Circuit
   The motor is the core component of the fan, and any malfunction can significantly reduce performance. A short circuit between motor windings can cause weak operation and increased temperature. Such failures not only affect the fan's performance but also pose safety risks.
   Solution:
   Use a digital multimeter to measure the resistance of the motor windings. If resistance values are abnormal, the windings may have short-circuited, and the motor needs to be replaced.

4. Decreased Start Capacitor Capacity
   Over time, the start capacitor's capacity gradually decreases, making it harder for the motor to start and causing a drop in speed. The start capacitor provides extra current during startup, and when its capacity reduces, the motor's starting torque weakens, slowing down the fan.
   Solution:
   If startup issues occur, replace the start capacitor. Opt for one with a slightly higher capacity to improve startup performance and long-term stability.

5. Overheat Protection
   Cooling fan motors are equipped with an overheat protection switch. When the motor or windings become too hot, this switch automatically disconnects the circuit to prevent the motor from burning out. As a result, the fan may stop or slow down.
   Solution:
   If the fan stops due to overheating, check the ventilation and ambient temperature. Ensure proper cooling, clean the motor and fan blades to prevent dust accumulation, which could cause overheating.

6. Wear or Lack of Lubrication on the Drive Shaft
   The drive shaft requires good lubrication to minimize friction and wear. If lubrication is insufficient or the shaft is worn, the rotation of the fan blades can be hindered, affecting the fan speed.
   Solution:
   Regularly check the lubrication on the drive shaft. If the shaft is not rotating smoothly, add lubricating oil to ensure smooth operation. If the shaft is severely worn, replace it.

7. Damaged Couplings
   Couplings connect the motor and fan blades. A damaged coupling can prevent the blades from rotating properly. This can occur due to prolonged use or external impacts.
   Solution:
   Regularly inspect the couplings. If any damage is detected, replace the coupling promptly to prevent further damage to the motor or other components.

8. Electrical Failures
   Electrical issues, such as damaged cables or loose connections, can cause an unstable power supply to the motor, which may reduce the fan's speed.
   Solution:
   Check all electrical connections to ensure they are intact and properly connected. If any electrical issues are found, repair them as soon as possible to maintain stable operation.

• Regular Cleaning: Clean the fan blades and motor regularly to prevent dust accumulation, which can affect cooling performance.
• Check Lubrication: Periodically check the lubrication levels in the motor and drive shaft to ensure proper lubrication.
• Capacitor Replacement: Replace the capacitor if it's damaged or its capacity decreases to maintain normal operation.
• Prevent Overheating: Ensure the fan operates in a well-ventilated environment and avoid excessive temperatures that could damage the motor.

As a professional cooling fan manufacturer, Ruiapple Electric is dedicated to providing high-quality, reliable fan products. Our cooling fans not only offer excellent performance but also undergo rigorous quality testing to ensure stable operation in high-load environments. With advanced designs and efficient manufacturing processes, our fans provide superior cooling solutions for various applications, helping customers enhance the efficiency and lifespan of their equipment.