Sounds and Smells Mean: Call a Technician

Woman at home on the phone

Your HVAC unit is a complex system that takes a lot of time and training to understand. Unfortunately, there is a list of things that can go wrong that only a technician may be able to diagnose. However, there may be certain sounds and smells coming from your system that you should be aware of as a homeowner.


Possibly the most unpleasant thing to deal with at home is something stinky. While we can’t get rid of unwanted smoke or pet smells, we can help with a few others.


Mildew and musty smells coming from your unit may mean you have a mold issue. Moisture tends to gather in vents and ducts, particularly in AC units, and if your draining solution becomes clogged, they become the perfect environment for mold growth.

It’s important to find the source and get it cleaned to keep the mold from spreading and further infecting your air quality.


An electrical burning smell is a sign that your unit’s circuit board or fan motor has shorted out. It could also mean another electrical wiring issue or an oil leak. A burning smell that is a bit more like exhaust fumes is a sign of a leak.

Keep in mind, if your system is starting up for the first time in a while, these burning smells are to be expected.


The most dangerous odor you can experience at home is a rotten egg smell. This means you most likely have a gas leak and should call a professional immediately. While waiting for them to arrive you should:

  • Open the windows
  • Leave the building
  • Alert any nearby neighbors
  • Wait for the professionals to take care of the issue


Machines will naturally make noises as they do their job. But some sounds are a sign that there may be something wrong internally and you should call a technician.


This could be irritating to hear as you’re sitting on the couch watching tv. Rattling is likely caused by a small object, like a toy or push pin, accidentally getting dropped into a vent. If it hasn’t fallen too far, you can simply reach in and grab the item yourself. But if you don’t see the noisy culprit, call a professional.

If the rattling turns to scraping, there may be a loose part in your unit. If it’s a part that shuts down your whole system, like part of your blower system detaching, you should address the issue and call your technician immediately to get back up and running.


High pitched squeaks, shrieks, and squeals are pointing towards a bad belt in need of lubricant or replacement. Your belt keeps the unit running smoothly and a bad one could slowly shut things down. Once your belt breaks, your whole system will shut down, so at the first squeal, call it in.

Common, Safe Noises

Some HVAC sounds happen as a result of the system doing its job. Some of them that you shouldn’t be alarmed by are:

  • Crackles - metal parts cooling down after the furnace turns off
  • Humming - the furnace burner lighting causes a humming sound
  • Pinging - ducts are expanding and contracting normally
  • Chirping - a typical furnace mechanics noise

Call in the Pros

Your HVAC system is an important part of your home which keeps your home comfortable. Keep any potential problems at bay by scheduling routine maintenance with Aire-Flo Heating & Cooling. Regular unit check-ups will give our technicians a chance to get to know your machine and troubleshoot any issues that may arise in the future.

Call us at (614) 585-8944 to schedule an appointment today, or contact us online.