The causes of noisy AC blower motor
It could be that you are feeling uncomfortable right now because you hear a noise when the car air conditioner (ac) is turned on. Worse, the noise disappears when the car ac is turned off.
Yes, the noise that appears when the car ac is turned on can come from various AC components. Still, the most common cause of noise in-car air conditioners comes from the car ac blower motor.
The ac blower motor function is to blow out the cool air from the evaporator into the cabin compartment through the air ducts and grilles. This blower motor is located inside the casing close to the AC evaporator. It is placed on the car's dashboard, precisely behind the front passenger dashboard drawer.
If the noise that appears when the ac is turned on sounds very loud at the back of the front passenger drawer, you can ensure that the car ac blower motor is the leading cause. So what are the causes of the noisy ac blower motor when ac is turned ON? Here are the reasons for the noisy ac blower motor.
1. An object enters the blower motor case.
The most common cause of a noisy car ac blower motor is an object entering the blower motor case. Such as leaves, paper, or plastic.
Leaves often enter through the front air inlet grille close to the glass and hood. In contrast, paper or plastic are often sucked into the ac blower motor case because the ac blower's location is generally close to the front passenger drawer.
Objects that enter the blower motor case will rub against the blower fan when it rotates, causing loud noise around the blower motor.
2. Worn-out bearing or bushing of the car ac blower motor
The bearing/bushing on the blower motor is the part that will hold the shaft of the blower motor to keep it rotating straight and evenly. This bearing/bushing will continue to rub against the blower motor's shaft to cause wear and tear on the part.
When the bearing/bushing of the car ac blower motor is worn and obliterated, the friction between the shaft of the blower motor and this bushing becomes harder. The friction will cause a loud buzzing sound, causing the car ac blower motor to make much noise when turned on.
3. Worn-out blower motor shaft
In addition to bearings/bushings, noisy car ac blower can also be caused by the worn-out blower motor shaft. This worn-out motor shaft can occur due to the rubbing part of the bushing/bearing that is too worn.
Because the ac blower shaft is used as the blower fan's support to rotate, the fan will become shaking when it turns. As a result, the blower motor fan can hit some of the walls/sides of the blower motor casing, causing the ac blower motor to sound and be noisy.
Also read:4. The blower fan's dust is too thick.
Another reason the car ac blower motor is noisy is because the blower fan's dust is too thick. Blower fans generally have fan blades that are not too wide apart. When too much dust sticks to the blades, it will naturally reduce the distance between the blades on the blower fan.
When the blower fan rotates, the narrow space in the blower fan blades due to this dust build-up can cause a whistling sound. The faster the blower motor is rotated, the louder the whistling sound will come out of the ac blower motor.
5. The blower fan is not symmetrical.
The last reason for the noisy blower motor we know is that the blower fan is not symmetrical. Blower fan asymmetry can occur because the fan mounting shaft is too hot and causes the blower fan's shaft holder to melt.
Melting of the shaft mount will cause the blower fan to be no longer symmetrical about the shaft and the blower motor. As a result, when the blower rotates, the blower fan will also turn into an unstable condition. This condition will cause the blower fan to rub against other parts of the blower motor or casing, causing the car ac blower to be noisy.