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5 Reasons for an AC Unit Rattling

5 Reasons for an AC Unit Rattling

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ac unit rattling - 5 Reasons Why Your AC Unit is Rattling - air conditioner on outside blue wall

There are several common explanations for an AC unit rattling. The most common causes of the noise tend to be loose screws, debris inside the outdoor unit, and a faulty or damaged fan blade or motor. This article will cover the reasons why you have a rattling air conditioning unit and how to solve the issue.

Why Your Air Conditioning Unit Makes a Rattling Noise

If your air conditioning system is running smoothly, you have probably become immune to its operational noise – no matter how loud its normal functioning is. 

However, it should be easy to pick up any concerning or undesired cracking, pulsating, or rattling sound. There is a likely explanation for each of them, so let’s go through the most common causes in a little more detail.

Bent or Damaged Fan Blades

  • An AC unit’s fan serves an essential function: It moves air across the condenser coil. If one of these fan blades is damaged, bent, or misaligned (due to everyday wear and tear, organic debris or rocks, or improper installation), it can cause a scraping or rattling sound.
  • The Solution: You will need to replace the AC unit’s fan blades. It’s best to let a professional do it because they can also use the opportunity to take a look at the fan motor shaft.


Debris in the Air Conditioner Unit

  • An outdoor AC unit is prone to have twigs, leaves, dirt, and rocks falling inside it. These foreign objects can also cause a rattling noise and, in some cases, damage the unit. Some seeds and organic debris can also stick to the AC fins and the condenser.
  • The Solution: Trim back any plants that are close to the outdoor AC unit and use a garden hose to spray the outside grill. If you need to open the unit and clean the inside, make sure you call a professional AC contractor that can also use solvents to remove any grass and seeds from the condenser fins.


Loose Panels or Covers in the Outdoor AC Unit

  • If your air conditioner unit received maintenance recently, there is a chance the cover panel wasn’t correctly reinstalled. There are a number of screws holding these panels in place, and if any of them is loose or not in place, this can cause considerable vibration and, subsequently, rattling noises.
  • The Solution: if you are handy, you can try adjusting the panels and cover of your AC system yourself. You will just need a nut socket or Phillips tip screwdriver to tighten all fasteners. If the noise persists after you have adjusted the panels, consider calling an AC technician to further explore the problem.


A Damaged or Faulty Motor

  • Inside an AC unit (and usually at the top of it), there is a fan mounted to a motor. The bearings in these air conditioning units tend to wear out and dry out, especially if they lack maintenance. 
  • They can also bend and be damaged by foreign objects such as debris and rocks. When the bearings wear out, you might notice the motor making a rattling noise or screeching. The sound will be even louder if the motor shaft is out of balance and has loose parts.
  • The Solution: You probably won’t be able to replace an AC motor yourself. A professional AC unit service technician can do it for you. This is usually a quick and affordable job and one you should do before the damaged motor causes harm to other parts of your air conditioning unit.


Other Reasons for Your AC Making a Rattling Noise

If you have gone through the above list and your air conditioning is still making a rattling noise, there are a few other things you can look at to determine the origin of the sound. These include:

  • Damaged or missing ISO pads: These pads are designed to reduce noise and vibration transfer. They can fail to do so if damaged.
  • Tight ductwork: If your ductwork is undersized, your blower motor could have trouble working and cause a rattling noise.
  • Clogged air filter: A dirty or clogged air filter can overwork the motor and cause noise.

Our Services

Hawthorne PHC specializes in installing and repairing AC units in Las Vegas, Reno, and surrounding areas. If you are looking for the best AC unit installation services, don’t hesitate to contact them and arrange a visit. The company’s technicians are available 24/7 and can provide numerous solutions for residential, semi-residential, and commercial installations.

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