No, That Wasn’t a Ghost: Strange HVAC Noises Explained

Had Edgar Allan Poe lived during the age of central heating and air, that tapping and rapping at his chamber door, or the beating of a heart hidden under floorboards, may very well have been the sounds of a malfunctioning HVAC system.

A heating and cooling system on the fritz can produce a number of eerie noises that, left unchecked, could drive a person...mad.

Keep your ears open for these ghastly sounds.

A Wraithlike Wailing

A ¼ horsepower motor operating at 1200 RPMs can make a spine-tingling squalor if it’s not lubricated or the bearings are out of alignment. Schedule an appointment with an HVAC technician immediately because you’ll be without heating or cooling if the motor breaks down.

A Bone-Chilling Banging

Ducts expand or contract with changes in pressure making very literal bumps in the night. If you can’t live with the banging and popping, you have a couple of options:

  • Insulate your ducts: Insulation has noise-canceling properties, but that’s just an ancillary benefit. Duct insulation minimizes heat loss, helping your HVAC operate more efficiently.
  • Replace your ducts: Square ducts are most prone to pop. Circular flex ducts are quieter because they can handle more pressure.

A Spectral Scraping

The blower wheel is responsible for moving large volumes of air through your ducts, so it can make a horrendous racket if something is out of alignment. The wheel can come loose and scrape against the casing.

A Hideous Hissing

That’s not a snake in your furnace room. Unless it’s a duct leaking, hissing is typically a simple fix. A furnace filter not sized correctly or not set right in the chamber creates gaps through which forced air whistles. Try resetting the filter. If you think you have the wrong size, consult the owner’s manual for the specified dimensions.

A Sickening Screaming

A high-pitched screaming could be a sign of a dangerously high refrigerant pressure or a failing compressor. Turn off your central air unit immediately and contact an exorcist...ahem...professional HVAC technician.

To schedule an appointment with Lex Air Conditioning and Heating call (972) 217-8955.