7 Different HVAC Odours You Can Encounter and Their Causes

Regarding your home comfort, the quality of your HVAC system can make a big difference. But sometimes, your system can emit strange odours. These smells can signal a system malfunction, so paying attention and investigating further is essential.

This blog post will discuss the seven most common HVAC odours, their possible causes, and the proper ways for HVAC repair.

1. Burning Smell

This is the most common HVAC odour. If you smell something burning, a system component is likely overheating. A lack of maintenance, an incorrect installation, or a malfunctioning part could cause this.

2. Musty Smell

If you smell something musty, it could be a sign of mould growth. Mould can grow in your ducts, ventilation system, or other HVAC system components. This is often caused by moisture buildup due to a lack of maintenance.

3. Chemical Smell

If you smell something chemical-like, it could indicate a refrigerant leak. Refrigerants are toxic, so a professional should check your system immediately.

4. Plastic Smell

If you smell something plastic, it’s likely that a component of your system has melted or is overheating. A lack of maintenance or a malfunctioning part can cause this.

5. Fishy Smell

If you smell something fishy, it could be caused by a buildup of dirt and debris in your system. A need for more maintenance often causes this.

6. Sewage Smell

If you smell something like sewage, a component of your system is likely clogged. A lack of maintenance or a malfunctioning part can cause this.

7. Petroleum Smell

If you smell something like petroleum, a component of your system is likely leaking oil. A lack of maintenance or a malfunctioning part can cause this.

What to Do When Your HVAC Has Odors?

Here are some tips on what to do when your HVAC has odours.

First and foremost, you should contact a professional HVAC technician at Legacy Heating to inspect your system. The technician will be able to diagnose the problem and provide you with a plan of action. Depending on the severity of the problem, they may suggest either a repair or a complete replacement of the HVAC system.

In the meantime, try to identify the source of the odour. If the odour smells like burning or smoke, it could indicate an electrical issue. Additionally, if the smell is musty or mouldy, it could be due to a moisture issue in the ducts.

Once you’ve identified the source of the odour, you should take steps to eliminate it. For example, if the odour is due to moisture, consider using a dehumidifier to reduce the humidity in the home. If the odour is due to an electrical issue, you should turn off the power to the system until you can get it serviced.

You should also check the furnace filters in your HVAC system. If the air filters are clogged or dirty, they can cause odours to be released into the air. Be sure to change the air filters regularly to ensure that your system is running effectively and to prevent odours from occurring.

Finally, call a professional HVAC technician at Legacy Heating & Cooling as soon as possible. They will be able to diagnose the issue and provide you with the best HVAC repair action.


If you encounter any of these odours, it’s essential to have your system inspected by a qualified technician. A skilled technician can pinpoint the problem and make the necessary repairs to ensure your system runs correctly. Paying attention to any strange odours your system emits can help you avoid costly repairs or system breakdowns in the future.

Legacy Heating is an HVAC company specializing in residential new home construction, HVAC repair, furnace replacement, and more. Our technicians are dedicated to reaching the needs of our customers and providing them with the best possible service. If you are looking for reliable HVAC services and products in Edmonton and Calgary, contact us today to learn more about our services and products.

HVAC Brands We're Proud to Carry

Legacy only uses the most efficient and cost-effective HVAC products. We pride ourselves on putting quality and customers first! We will equip your new home with the best HVAC system and offer the most reliable residential heating service in Edmonton and Calgary.

Contact Us Today

We’ll help you find the right heating and air conditioning system for you and your budget.

Edmonton Area 780-733-1256 Calgary Area 403-451-1337

Honesty, Integrity, Legacy