A/C operation, normal noises.
Normal noises include the sounds of A/C compressor clutch engagement, the blower motor, moving blend air and mode doors, and pressure equalization after vehicle is shut down.
Noises that could indicate the need for a/c compressor service or replacement include:
- Growling noise with compressor disengaged
- Whistling noise
- Grinding noise
- Squealing noise
- Rattling noise
- Growling noise with compressor engaged
- Banging noise
- Knocking noise
Why is my AC making a weird noise?
Banging noise: If liquid refrigerant enters the compressor, a thumping, banging noise will result.
Knocking noise: Heavy knocking compressor noises come from refrigerant system blockage, incorrect pressures, or internal damage.
Growling noise with compressor disengaged: A worn compressor pulley bearing or clutch bearing will cause a growling noise.
Growling noise with the compressor engaged: A/C compressor internal bearings damage.
Squealing noise: A loose, dry, or worn A/C compressor belt will cause squealing noise. This noise will be worse during acceleration.
Worn or dry blower motor bearings may cause a squealing noise when the blower motor is running
Rattling noise: A loose or worn clutch hub or loose compressor mountings bolt will also cause rattling noise from the compressor.
Knocking noises: This type of noise from the compressor usually indicates internal damage, especially on piston-type compressors. Always check the compressor mounting and brackets before condemning the compressor for noise.
A loose mounting can cause knocking noises from the compressor area that may be mistaken for internal compressor noise.
Grinding noise: When car accessories pulley bearings are failing, they can make this kind of noise.