Air conditioner motors are an important noise source for air conditioning systems, especially indoor units of air conditioners. The frequency of electromagnetic noise of the motors is low and the tone is close to a single frequency pure tone. The working condition of the motor can be judged by identifying the noise of the air conditioner motor.
There are many ways to identify motor noise. A practical load replacement method is now introduced. There are various reasons for the electromagnetic noise of air-conditioning motors, and their characteristic frequencies are generally related to the power frequency.

With a simple load replacement method, you can distinguish between abnormal vibration caused by uneven magnetic fields or vibration caused by excessive load. Take an air-conditioning indoor fan as an example, the motor noise frequency has a peak value of 600 Hz. Because its frequency does not change with the speed of the motor, and the noise disappears with the power cut off, it is determined as the electromagnetic noise of the motor.
Electromagnetic noise is generally caused by poor electromagnetic design, abnormal electromagnetic vibration caused by loose stator and rotor. In order to determine the source of electromagnetic sound, the method of changing the load is adopted.
The loads that affect air conditioning fans are

• Weight of wind blade
• The position where the center of gravity of the blade is loaded on the motor shaft