Key Takeaway
Some noise from your HVAC system is normal. However, these seven scary HVAC sounds can indicate a real problem. If your AC system is humming, banging, squealing, or bubbling, find out what the likely cause is and when you should call a professional.
Is your HVAC going bump in the night? (Or, for that matter, in broad daylight?) Your HVAC may make a variety of sounds, including whistling from your air ducts or noise from the fan. However, some noises warrant a lot more concern than others. Here are seven noises you should never ignore:
1. Buzzing or Humming
This is usually an electrical problem. If it continues when the unit is not operating, it may indicate an electrical problem that should be inspected by a professional. If the outdoor unit is humming and the fan is not starting, you probably have a capacitor problem, which requires a professional. It can also be the result of a faulty contactor, wiring issues in your compressor, or simply a loose wire somewhere.
If your unit starts making scary HVAC sounds like buzzing or humming more loudly than usual, you should call in a professional to check for possible causes and fix the problem. As electrical problems can be a fire hazard, you should get this checked out right away. Mechanical humming may indicate you need to remove debris from or adjust the fan motor, and failing to do so can result in your unit breaking down.
2. Banging, Clanging, or Thumping
This typically means something is loose or broken: a detached fan blade, broken motor mount, or even some loose ductwork. A thumping noise that increases during startup or shutdown can mean your blower wheel is out of balance.
This is another time to call a professional before the problem gets worse and leaves you without AC when you need it most.
3. Screeching or Squealing
Wailing like a banshee typically results from a loose belt or poorly lubricated bearing. This is much more common with older systems; modern systems don’t have belt-driven motors.
Again, not addressing such scary HVAC sounds can lead to a complete breakdown of your system, likely when it’s facing particular strain or otherwise at the worst possible moment. If you have a system with belt-driven motors, it may be time to think about upgrading to something newer and more efficient.
4. Whistling or Hissing
Some whistling or hissing in your ducts is normal. It’s caused by high air velocity. But if your system starts whistling or hissing more or is doing so on startup, this indicates restricted airflow somewhere.
Check your vents and remove furniture or debris. Sometimes it’s as simple as a dog or a child dropping a toy in just the wrong place. This can also be caused by clogged air filters. Make sure to change or clean your air filters as recommended by the manufacturer, and consider doing it more often if you have pets. Dirt on the coil or blower and closed dampers can also reduce airflow.
If you can’t find another cause, get your ducts inspected. There might be something in them, like a mouse nest, blocking the flow.
5. Hissing or Bubbling
Does your outdoor unit sound like a witch’s cauldron? This can indicate a refrigerant leak, but it’s normal if your system is entering defrost mode. The bubbling may be coming from the refrigerant line. Call a professional to check for leaks rather than just topping up refrigerant.
It can also be caused by air pockets in the refrigerant, although this too is often linked to low refrigerant. Try removing debris from the outdoor unit first, as that can sometimes cause all kinds of noises.
6. Clicking
A damaged fan or minor motor issue can cause clicking during operation. This is also worth checking on because you can catch the problem early before it becomes something worse.
If you hear clicking before startup, that’s probably an electrical issue and should also be checked out.
7. Grinding
Last but far from least, any scary grinding sounds from your compressor should prompt a quick call to a professional! Like screeching, it can indicate a lack of lubrication, which means parts are rubbing against each other
This can cause overheating and system failure. Your system may simply shut down if it overheats, leaving you with no climate control.
Don’t Ignore Unusual AC Noises. Get Help Today.
If you hear any of these scary HVAC sounds from your system, it’s time to get it checked out. Don’t be intimidated! Contact Kabran to schedule an inspection quickly before your thumping or bubbling becomes a broken AC unit and an expensive repair.
