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All about HVAC vents burning smells

by Tooba Aftab Ahmed | on February 08, 2018

After sensing a sudden burning smell, what is that you quickly think of? The first few thoughts push you to run towards your costly appliances, or the others like iron, hair straighteners etc. These are the most probable appliances to cause a burning smell but guess what? The burning smell coming from the HVAC vents is also a common smell but homeowners take too long to discover it. And the late discovery often leads to worsening the problem. So the next time you sense a burning smell, don't be late in checking your HVAC vents.
Here we discuss some of the most common causes of HVAC vent burning smells.

Burning smell from cooling unit

A burning smell coming from the cooling unit; Air Conditioner is always a sign that something bad is on the way. This could mean:

- An overheated motor or compressor
- A short-circuited circuit board
- Gas leaks
Keep in mind to quickly turn off the system as soon as you discover that the smell is coming from it or any of its component. Regarding the last point, here is some insight; The gas used in cooling appliances is odourless. But because it is harmful, a chemical causing a smell is added to it in order to alert of its presence. That smell can be compared with the smell of a rotten egg, garlic or sulphur. Such a smell from the air vents is a clear indication of the gas leak.

Burning smell from cooling unit

Contrary to the burning smell from an Air Conditioner, the burning smell from the Furnace is a common scenario. But not all burning odours are harmless. The one that is harmless is that of the burning of dust and debris that comes when the unit is turned on after a whole season. Initially, the dust that goes from the ductwork or the one that is accumulated there in the Furnace burns to give a burning smell so no need to worry about that. But beware if this continues even after long. The smell that comes when the unit is in use for already some time, it could mean, similar to what it means for the Air Conditioner;

- Overheating of motor or fan.
- Short-circuiting
- Burning of paper (on any other item that may have fallen into the ductwork)

For all of these, the first to-do is to shut the system off and call a professional to diagnose and resolve the problem.

Note : If you ever find yourself stuck in such a situation, call us anytime and our professionals will be there ASAP.
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Common causes of HVAC burning smells

To keep things easy for yourself and to know at the time of emergency what components to check, keep these common causes of HVAC vent smells in mind:

- Dirty Filters :
Dirty Filters block the passage of air and the fan and motor have to put additional effort in order to let the air pass through those dirty filters. This causes burning smell from the components as they heat up. To avoid such odour and havoc, change your filter every 3-6 months.

- Belt-Drive fan motor :
A motor which is a belt drive motor has a rubber belt that oftentimes burn or ages and causes smells. The belt, therefore, in itself is a cause of smell and thus should be changed if it is damaged or over aged.

- Motor overheating
As discussed above, for the Air Conditioner as well as the Furnace, one of the most common causes of burning smells is an unmaintained motor that has to overwork or the one which is overused. To avoid such a case, keep your units well maintained with annual and bi-annual maintenance & cleaning and avoid over usage as it decreases the lifetime of the appliances.

- Burning electrical components
The failure of electrical components or the wirings can lead to severe burning smells. As the plastic around the wires burn, a staunch smell does the work of alarming you of the situation. This could take place as a result of short-circuiting. Quickly turn the power off and don't think of a DIY. Call only a professional to fix the problem.

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