Why Your AC Is Making Rattling Noises

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Rattling noises from the air conditioner (AC) are not just bothersome —they also signal that something is wrong with the AC that may need repairs. Diagnose such noises with a professional as soon as you realize them to prevent further damage. Below are some of the typical causes of rattling noises from the AC.

Worn Isolation Pads

A typical AC has multiple moving parts. The moving parts emit some vibrations as the AC runs, and the vibrations transfer to other parts of the AC. AC manufacturers use isolation pads between the AC and its base to dampen the vibrations.

The isolation pads are subject to wear and tear, just like other parts of the AC. An uneven AC base increases the rate of wear and tear. If the isolation pads wear too much, the vibrations increase and can even transfer to the house.

Overly Tight Refrigerant Lines

Changes in refrigerant pressure cause small movements in the refrigerant lines. The refrigerant lines should have some flex in them to accommodate these movements. The lines might rattle if they are too tight. The ratting will also increase the lines' rate of wear, which might lead to refrigerant leaks down the line.

Loose Hardware

Loose parts of the AC can also rattle if they hit other components. For example:

  • The AC motor can rattle due to damaged motor mounts or loose internal parts.
  • The unit cabinet can rattle if its panels are loose (for example, due to dislodged screws).
  • The registers can rattle due to the pressure of the air passing through them – mostly if the return air is inadequate.

The above are just a few examples. Other parts of the AC can also rattle if loose.

Struck Debris

As previously mentioned, the AC has multiple moving parts. If a solid object is stuck in the AC unit, it can produce rattling noises as the moving parts hit it. Objects stuck in the grille can also make the same sounds. Pebbles, toys, and tree branches are common culprits.

Misaligned Fan

Lastly, a damaged or misaligned AC fan can also make rattling sounds. With damaged fan blades or misalignment, the fan blades will keep hitting the casing. The fan will eventually fail if you don't fix the damage.

Wear and tear means that an old AC is more likely to rattle than a new one. Regular service of the AC may help you avoid some of these issues. Contact an AC contractor if your AC is rattling. Prompt repairs will save you costlier repairs down the line. For more information about an AC repair, reach out to a local HVAC company.


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