Why Is There a Burning Smell Coming From My Heat Vents?

Have you recently noticed a burning smell coming from your heat vents? 

Assuming you’ve already ruled out a house fire, this smell could be normal. It just depends on whether it’s the beginning of heating season or not.

If you just turned on your furnace for the first time this winter, a burnt smell is normal. You see, for 5 months your furnace has been collecting dust. So when you start it up for the first time, you’ll smell that dust burning off inside the unit. 

But if the burning smell persists after the first 24 hours of turning on your furnace you may have a larger problem. Your furnace could be producing a burning smell because of the following issues:

  • A clogged air filter 
  • Problems with the oil burner
  • Electrical problems
  • Failed capacitor

We’ll go over each of these items and show you what you can do to determine which one is your issue. 

Problems that cause a burning smell from your heat vents

A clogged filter

The first thing you should do if you smell a burning smell coming through your air vents is to check your furnace’s filter.

If it looks like the filter on the right, you need to replace it immediately.


Well, when an air filter becomes clogged it stops working, which allows dirt and dust to enter the system. This dirt and dust will eventually make its way into the heat exchanger and burn up.

Once you’ve replaced the filter, turn on the heat and see if the burning smell disappears over time. If not, continue reading to see which of the following issues might be causing the smell…

An oil leak

Brand new furnaces are coated with oil to keep heat exchangers from overheating so if your furnace is new and there is a slight oil scent that accompanies the burnt smell, this is most likely normal.

But if your furnace is an oil-fired furnace and is not new, you most likely have a crack or misalignment in the oil burner. That would allow smoke from the unburned oil to enter the system and get blown into your home.

If you see soot around your heating vents and smell oil, this might be your issue. You’ll need to contact a professional to repair the oil burner.

Electrical problems

If the burning smell coming from your vents smells slightly electrical or plastic, you need to call a professional immediately. This is most likely coming from worn out or damaged wiring, which is extremely dangerous.

Problems with the electrical wiring of your furnace system can easily start an electrical fire, so don’t wait to get this fixed.

Failed capacitor

A capacitor is a small, cylindrical device that is attached to the furnace’s blower motor (the fan that pushes heated air through your home). It stores electrical power and acts like a battery to give the blower motor the extra kick of electrical “juice” it needs to get started.

But capacitors, like batteries, get weak and eventually will need to be replaced. When this happens, the blower motor will try to compensate for the extra power it’s missing at startup and will consume more electricity than it can handle. 

This can cause your blower motor to overheat and even create smoke. Once that smoke and burning smell gets circulated into the duct system, you’ll soon notice the smell coming through your heating vents.

You’ll know your capacitor needs to be replaced if it:

  • Oozes liquid
  • Has a “mushroomed” or swollen top

If you think you have a failed capacitor, we suggest having a professional replace it.

Need help from a MN tech?

If that burning smell coming from your vents won’t go away, you probably need a professional to inspect your furnace for issues.

If you live in the Minnesota or western Wisconsin area, schedule your appointment with a professional at On Time Service Pros.

As always, we promise to be on time...or it’s free!

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