9 HVAC Noises And Their Possible Explanation

Discover common HVAC noises like AC banging noise and AC buzzing sound. Learn their possible explanations and find solutions at Sandium. Contact us for assistance!

Updated on Oct 22, 2023
5 min read
9 HVAC Noises And Their Possible Explanation

Air conditioners have become quieter than ever with two-stage (variable speed) compressors and sound-dampening technology. This is why it is important that you take notice whenever your air conditioner makes funny sounds in your Bay Area home or business.

These are a few reasons why your air conditioner may be making noises:

1. Banging Noise

Banging is a sure indicator of a broken or loose part. This can be a crankshaft, piston pin, or connecting rod within the compressor. It is possible that the indoor blower has become unbalanced. Banging noise may also signal that you need to change the compressor.

2. Clanking Noise

Clanking is another indicator of out-of-balance or loose component. It is possible that the parts within the sealed unit have failed. The compressor could have become loose requiring a replacement. The sound can also mean that the blades in the outdoor fan or indoor blower are hitting other parts.

3. Clicking Noise

Electrical components make a clicking sound at start-up and shutdown. This is normal. However, ongoing or constant clicking is not normal. This is a sign of failing or defective thermostat. An air conditioning system has several electrical parts which makes it necessary to pay attention to electrical issues.

4. Buzzing Noise

Buzzing noise from the outdoor unit can indicate:

  • Loose motor in outdoor fan
  • Loose parts
  • Dirty air filter
  • Out of balance blower
  • Dirty condenser coils
  • Refrigerant leak

If your HVAC unit is unable to cool the house as before and is making a buzzing sound, the problem is surely a refrigerant leak.

5. Squealing Noise

Fan and blower noises, such as squeals, squeaks, and rattles can be transmitted through the ductwork. Indoor blower motors and outdoor fan motors squeal loudly when malfunctioning. However, this sound is normal during start-up.

6. Humming Noise

Humming is not usually serious, but it signals that there is something wrong with the air conditioner. Loose refrigerant piping and parts can create vibrations if left unchecked. This can create more serious maintenance issues. Buzzing or humming sounds can also point to electrical concerns.

7. Rattling Noise

Rattling in an air conditioner can mean that the unit is beginning to deteriorate. Another reason could be that leaves or twigs have clogged the outdoor unit. Electrical contractor can make a chattering sound. If left unchecked, this may result in the compressor and other components getting damaged. Fan may be another culprit if loose.

8. Screaming Noise

High pitched screaming or whistling from an HVAC unit is not a good thing. You should turn off the unit immediately and call a professional. This is usually owing to a refrigerant leak that won’t just damage the system, but also threaten your family’s health. Screaming sound can be because there is high internal pressure in the compressor. This is a dangerous condition. Don’t panic if the air conditioner turns off on its own. This is just the safety switch doing its job.

9. Pulsating Noise

Pulsating sounds are generally not bad when the air conditioner is operating. However, if the unit is making a pulsating sound which can be heard inside the house, you should have a technician check the unit. There could be something loose. Most likely there may be an issue with the fan blades or motor. However, any loose part or panel can cause a pulsating sound to emanate from the air conditioner.

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