It’s natural for your heating and cooling equipment to make some noise during standard operation. A mini-split system is no different, despite their unique and compact design. But certain noises may be evidence that a problem is brewing.

Tokay Heating & Air would like to help. We’ve listed a few common mini-split noises and what they might mean for your HVAC equipment. As you become more familiar with these sounds, you’ll be better prepared to request professional help. The faster a problem is addressed, the more the risk of severe damage is minimized.

• Crackling/Rattling Sound: These kinds of noises are frequently metallic, and most often mean something is loose. Since mini-split systems are made up of two or more units, you’ll want to inspect them all. If a bolt is coming free, refastening it may resolve crackling noises. The fan or motor may also be damaged or loose, making noise as it rattles against the rest of the mini-split.
• Buzzing/Humming: A mini-split buzzing noise is also common. Similar to vibrating or humming, this could be an electrical malfunction with the outdoor unit’s compressor. When the compressor is humming or buzzing, it’s usually because the system is handling an unusual number of amps. Unfortunately, electrical problems like these are more complicated to properly diagnose. They are best handled by a certified and insured professional.
  Occasionally the mini-split condensate pump naturally produces a similar noise. Some homeowners can use insulating foam to reduce this noise.
• Whistling or Histting: A hissing noise is troubling, particularly if it’s coming from the indoor unit. Cooling equipment should not make whistling or other high-pitched noises. The most common cause of these types of sound is a refrigerant leak. Sometimes the leak is a result of a loose or damaged valve. But if the coils are damaged, resolving the problem will be more time-consuming. Both the coils and the refrigerant will need to be replaced.
  If left alone, a refrigerant leak could be disastrous. It can irreparably harm the compressor, which is usually more severe than what mini-split AC repair can provide. An entire unit may have to be replaced, something we want you to avoid whenever possible.