TL;DR: Banging, rattling, or burning smells from your HVAC system aren’t "normal" — they're warning signs. From loose parts to clogged filters to electrical issues, this guide helps Guelph-area homeowners decode what their HVAC is trying to tell them.

Most of us get used to the hum of the furnace or the whir of the AC, but when your HVAC system starts banging, rattling, or smelling like something's burning? That's your system calling for help.

In Guelph, Kitchener, and Waterloo, we see a lot of HVAC issues that start with weird noises or odours — and trust us, ignoring them rarely ends well.

1. Banging, Clanging, or Thumping

These sounds usually mean something has come loose. It could be a blower wheel, motor mount, or ductwork. Left alone, these parts can break entirely or damage other components.

If it sounds like metal hitting metal, turn the system off and give us a call. We'll check the interior of your furnace or AC safely and fix the problem before it gets worse.

2. Hissing or Whistling

A constant hiss or whistle could mean a refrigerant leak (in your AC) or an issue with air pressure in your ducts.

Refrigerant is hazardous to handle, so never try to DIY this one. Instead, schedule an inspection with a licensed tech who can test, patch, and recharge your system.

We offer ductwork installations and repairs across Cambridge and Waterloo to restore proper airflow and balance.

3. Rattling or Vibrating

This often points to loose panels or components, especially after seasonal shifts. It might be something simple, like a loose screw, or something more serious like an issue with your fan blades.

A quick system check can tighten things up before they shake themselves into failure.

4. Burning or Musty Smells

That burning smell? It could be:

• Dust burning off after a long break (normal, briefly)

• A dirty filter restricting airflow

• Overheating electrical components

A musty smell, on the other hand, often signals mold or mildew in your vents or ductwork.

If it lingers for more than a day, have your ducts inspected and cleaned. Our duct cleaning services help remove odours, allergens, and buildup.

5. Clicking, Buzzing, or Constant Humming

These usually indicate electrical issues. Clicking at startup might be a failing capacitor. Buzzing could mean a contactor issue. Constant humming might point to a problem with your blower motor.

Electrical issues should always be handled by a licensed HVAC technician.

We handle furnace installations and repairs throughout Guelph and Kitchener, and we’ll make sure your system is safe to run.

When in Doubt, Shut It Down and Call

Unusual noises and smells mean something isn’t right. Continuing to run your system can cause bigger problems or even pose safety risks. If you notice anything off, it’s best to power down and give us a shout.

Give us a call at (519) 835-4858 for a Free Quote!

B.A.P Heating and Cooling serves homeowners in Guelph, Kitchener, Waterloo, Cambridge and nearby communities with honest inspections and fast repairs that won’t leave you in the cold — or sweating through the summer.

Let your HVAC system work quietly and cleanly again.