If your HVAC system is making noise, it doesn’t always mean something’s wrong. Some sounds are normal, especially if you’re running your A/C 24/7 in the summer.
But sometimes, sounds can signal a serious issue with your equipment. Knowing the difference between typical and unusual sounds can help you avoid unnecessary stress and costly repairs down the road. Below is a breakdown of the most common HVAC noises, including what’s normal, what’s not, and when to call in the pros.
Normal HVAC Noises
Humming
A low humming sound is typical when you’re using your HVAC unit, especially from the compressor and fan motors. If your system has always had a hum, it’s probably nothing to worry about. Some components, such as transformers, hum softly as part of their normal operation. Even a new transformer might hum or buzz a bit louder than you’re used to hearing. It’s also normal for humming to get louder as parts age and time goes on.
Generally, you should only worry if the hum is new, much louder than usual, or turns into a noticeable buzz. This could mean an electrical issue or failing part.
Whooshing
Have a heat pump system? That noise is totally normal. It comes from the reversing valve in the outdoor unit, which, when changing the direction of refrigerant flow, can make a sudden whooshing sound that can echo throughout the house. Though it may sound concerning, fortunately it’s harmless.
Clicking
Clicking sounds are also common. Relays, thermostats, and other electrical components often click, especially when they’re turning on or off. If you’ve recently had a part or thermostat replaced, you may find the click is more noticeable, but it’s still probably normal. Some relays, a switch that controls the flow of electricity to your HVAC components, may even sound as loud as a slap, but this is also normal.
However, you’ll want to watch out for constant or rapid clicking (not just at start-up). This might mean you’re dealing with a control board issue or a faulty relay.
Problem Noises to Watch Out For
If you’re hearing any of the below noises, it’s time to investigate further or call your trusted HVAC technician.
Banging
Banging is never normal. It often points to a loose blower wheel, damaged fan blade, or internal problem in the compressor. Continuing to run your system could lead to bigger and more expensive repairs.
If you notice banging, shut off the system and call a professional right away.
Screeching, Whining, or Squealing
High-pitched sounds usually come from a failing blower motor. As the bearings wear out, the motor will start to whine or squeal, and the noise often gets worse over time before it fails entirely. These parts aren’t designed to be oiled anymore as they are enclosed, so replacing them is the only solution.
Rattling
Rattling can be tricky. It might be something minor, or it could signal a future problem. Outdoor unit rattling is often just refrigerant flowing through the system, which is normal. But indoor rattling could mean refrigerant lines are vibrating against each other or another surface. This can eventually cause a leak.
To test it yourself, gently press on the HVAC panel. If the rattling stops, it may just be a loose panel. This type of rattling isn’t a problem, though the repetitive sound can be annoying; some strategically placed tape or cardboard can typically help silence that. If the rattling continues, it’s time to call in the professionals for a closer look.
When in Doubt, Call the Experts
Not all HVAC noises are cause for panic, but some are warning signs you don’t want to ignore. If you hear banging, screeching, or a new noise you’ve never heard before, don’t wait. At North East Air Conditioning, Heating & Plumbing, our experienced technicians can identify the issue quickly and offer solutions that fit your budget.
What’s more, our service contracts waive the service call fee for all contract customers—so we’ll come check out any odd noises for no charge to contract customers. This agreement helps give you peace of mind without worrying about paying for a nuisance call.
As a family-owned and operated HVAC company, we’re proud to serve our neighbors with honest, knowledgeable HVAC and plumbing care. Whether it’s a worrisome rattle or routine maintenance, we’re just a call away.
