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Why Are Your Ducts Rattling?

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There's nothing like firing your air conditioner for the first time every summer and feeling that refreshing burst of cold air. Of course, sometimes that deliciously cool air is accompanied by unusual and disconcerting sounds. While central air conditioning systems can often be a source of many strange noises, few are as frustrating and annoying as a ubiquitous rattle emanating from the vents. Depending on the underlying cause of the problem, you may only hear this rattle when the blower first engages or you may hear it continuously as the fan runs. If you want to enjoy the peace of a properly running AC system, you'll need to get to the bottom of this irritating noise.

Identify The Type Of Noise

A rattle is a rattle, right? It may seem like there isn't much to be gleaned from obsessing over the kind of rattle coming from your vents, but this small piece of information will provide important clues to the underlying problem. The key question at this phase of the diagnostic process is whether the rattle is originating in the vent covers, the ductwork, or deeper in the system. To help get to the bottom of the problem, ask yourself these questions:

  • Is the noise audible throughout the home or only in one location?
  • Is the noise continuous, or does it stop once the blower is running?
  • Is the noise a harsh metallic rattle?
  • Does the noise sound more like a soft, non-metallic rustling?
  • Are there additional squeaks, bangs, or other sounds accompanying the rattle?

As a general rule of thumb, noises that are highly localized are likely to be the result of loose register covers. On the other hand, softer rustling noises audible throughout the home are typically caused by the flexible ductwork found in many newer homes. On the other hand, harsh metallic noises often originate with the blower unit.

Going Deeper

Once you have a rough idea of where the problem might lie, you can begin to conduct more in-depth troubleshooting. If you think the issue is localized, the solution is often simple: check to see if your vent covers are loose and tighten any that seem suspect. If this doesn't solve the problem, then the fault can likely be found in either the ductwork or the blower.

Since do-it-yourself ductwork diagnosis is beyond the capabilities of most homeowners, your next step should be to check the air handler unit. If the blower motor or fan is suffering from a failure, then it should be clearly audible from near the air handler unit. Short squeals or clanks often indicate a problem with the blower motor or the fan itself.

Rattles that don't seem to clearly originate from a vent or from the air handler are likely coming from the ductwork. In this case, hiring a professional AC contractor to diagnose and locate the problem will be your best option. Although rattles like this may seem annoying, they often indicate deeper problems that should be resolved quickly to ensure your AC continues to function efficiently. For more information, reach out to a company like Bergmann Heating & Air Conditioning today.


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