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Why Does My AC Unit Smell Funny When I Turn it On?

By April 18, 2019January 29th, 2022Air Conditioning, HP News, HVAC, Tips
BR McGinty Smelly A/C

Now that we are well into our summer months, now might be a good time to bring up the topic that a lot of you may be wondering about: the odor that is emitted from your HVAC unit. We are steadily having to use our air conditioners on a more regular basis as we progress further into the summer. You may have noticed that there is a strange odor when you run your unit. What sort of odor is it?

Why Does My Air Conditioner Smell?

Depending on the kind of smell—if you can put your finger on it—it could be any number of things causing it; meaning there could be any number of ways to fix it. Throughout this blog post we are going to try to help you diagnose the smell which will in turn help you to alleviate the problem.

Musty Smell

If the air that is coming through your supply registers is reminiscent of a wet towel, mildew could certainly be your problem. What this means is that there could be mold and/or fungus growing in or around your outside AC unit. This is a very common problem. As we have stated in previous blog posts, an HVAC unit not only adjusts the temperature inside of your home, but it also eliminates or lowers the humidity levels as well. If your compressor is not drained properly, mold and mildew may grow on any lingering moisture. You may also consider changing your unit’s filters, as this is often the cause for this particular odor.

Rotten Smell

This smell can usually be boiled down to one root cause: dead animal(s). This is probably the issue if the smell that you are experiencing is of a “spoiled” nature. Animals will, especially during the winter months, seek shelter inside of your HVAC unit. It is not advisable for you to clean the unit out yourself if this is the issue. There are many health hazards that are connected to dead animals, especially if they have been sitting a while. Contact us immediately and we will gladly come out to help you in this instance.

Sewage Smell

This one, while self explanatory, can be one of the most hazardous causes of odor. This usually means that there is a backup in the sewer system. This can be caused by a sewer vent pipe that has ruptured near ducting. When this happens, even the littlest bit of methane that could leak into your ventilation system can be incredibly dangerous. If this is the case then it is important that you contact us immediately to rectify the problem.

Vinegar Smell

The smell of vinegar coming through your supply registers usually points to stagnant water in your unit that isn’t drained properly. As you recall from the information regarding the smell of mildew, if this issue isn’t taken seriously and is forgotten then it’s likely that mold and mildew will become an issue later down the road. The sooner you address this smell the less damage you are doing to your HVAC unit.

Burning Smell

It’s safe to say that if you have a burning smell coming through your vents then you are experiencing an electrical problem, hence the burning smell. These problems often happen to older homes because their units have usually been around for a while. All it takes to fix this smell is replacing the circuit board (which has likely shorted) and/or replace the blower fan because its motor has burned out. We here at BR McGinty take care of both of the above listed issues regarding electrical problems with your unit.

As you can see, it’s important for you to identify what kind of smell you are experiencing in order to adequately respond to it. So turn your AC unit on this afternoon—is there a smell? What kind? If you need any sort of help whatsoever, be sure to give us a call so we can come on over and fix the problem.

And what if when you turn your unit on it doesn’t necessarily smell, but there is a terrible squealing noise? Well, that’s something that we can help with as well. Click this link for more information on what can be causing that terrible noise!