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Michall Daimion Heating & Air Conditioning, Inc. Blog

Rundown on Common Worrying AC Sounds


Air conditioning systems aren’t necessarily “quiet” systems (although advancing technology has reduced the amount of sound they make). You expect to hear several sounds as your home’s AC runs: the fans, the motor powering the compressor, the drip of water from the condensate pan, and the movement of air through the ductwork. It’s an easy set of sounds to become accustomed to until it turns into part of the soundtrack of summer—a soothing white noise for hot days.

Then … something strange interrupts the AC soundscape. Something odd, or loud, or unexpected. Could it be a malfunction in the AC?

It might, and we’re going to look over a few of the more common cautionary sounds you might hear from your air conditioning system. When in doubt, you’ll want to have trained HVAC technicians on the job to see what’s wrong, and what needs to be fixed.

A Guide to the Common AC Warning Sounds

Here are the most common kinds of noises you’ll hear from an AC that indicate something may be wrong.

  • Rattling: Although this is an alarming sound, it may be something simple. Check to see if the door of the AC cabinet is latched. If this isn’t the problem, you may have a loose part inside the air handler, or the cabinet is loose on its foundation. Have a technician find the source of whatever is loose.
  • Clanging: This sharp metal clanging noise from either the indoor or the outdoor cabinet often means a bent fan blade that’s striking the outer casing. Turn the air conditioner off immediately to avoid further damage and then call for repairs.
  • Shrieking: A high-pitched metallic shrieking is a warning that the bearings in the motors are wearing down. If the bearings wear out completely, the motor will fail. If you have a technician replace the bearings in time, you’ll prevent further damage to the motor—so make sure you act right away.
  • Grinding: This is another motor warning sound, but it often indicates the motor is on the verge of burning out because of mechanical stress. Technicians may be able to rescue it, but you’ll likely need to have a new motor put in.
  • Clicking: Clicking sounds are often due to failing capacitors, the electrical components that send voltage to the motors to start them and keep them running. Capacitors will usually fail before the AC system does, so you can expect to need to have them replaced at some point in the unit’s life.
  • Hissing: This probably leaking refrigerant. You’re heating the high-pressure refrigerant gas escaping from the lines. Loss of refrigerant can put the entire system in danger if it isn’t corrected. Call technicians to find the leaks, seal them, and then restore the proper amount of lost refrigerant.

When you need air conditioning repair in West Chester, PA, call on our experienced team. We offer 24/7 emergency service and have the finest NATE-certified technicians.

Michall Daimion Heating & Air Conditioning, Inc. has been the Main Line’s Premier Service Provider since 1976. Call us for air conditioning repairs done right.

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