Of all the major appliances in your home, chances are there is one that you barely notice it until something goes horribly wrong: your HVAC system. There are several, pretty obvious signs that there is something wrong with your heating and air conditioning unit, such as cold air coming from the furnace or if the system won't even turn on. However, what about some of the less clear signs that there is danger, including a strange odor coming from the registers. Here are three potentially dangerous HVAC odors that you should never ignore.

Rotten Egg Odor

You should especially be mindful of the smell of rotten eggs. If you smell a sulfur-like odor coming from your HVAC system, it could indicate a natural gas leak. The smell of rotten eggs or garlic associated with natural gas isn't actually the gas itself. It is an additive that is used by utility company to warn customers of a natural gas leak.

If you notice a rotten egg smell, don't take a chance and instead, contact your utility provider immediately. According to Quake Energy, the intensity of the odor should dictate whether or not you leave your home. If the odor isn't strong, your utility provider might recommend opening up some windows and making sure the furnace or your stove's pilot light isn't on.

However, if the smell of rotten eggs is intense, your utility provider will insist you leave your home right away. Alert your neighbors about the potential gas leak and insist they also leave the neighborhood. Don't attempt to find the source of the leak and instead, allow the utility company to remedy the problem.

Musty Odor

The smell of mold is probably one of the most common issues that comes with having an air conditioning unit. The air conditioner is constantly producing moisture, and when this liquid doesn't drain properly, it can lead to serious mold and mildew growth inside your HVAC duct system.

If you notice an intense musty odor coming from your HVAC system, don't hesitate to contact a professional right away. The technician will have the tools and experience necessary to discover why your air conditioner isn't draining properly, fix the problem and clean out the mold from your HVAC system's ductwork.

It is especially important that you stop using your air conditioning unit and call a professional HVAC technician immediately if anyone in your home suffers from a mold allergy. The mold formation in your HVAC duct system typically isn't life threatening, but it can cause any allergy sufferers in your home some extreme discomfort.

Smell of Burning Dust

When you turn on your furnace for the first time in the fall or winter, chances are you will notice a burning odor. Typically, when this odor dissipates within a few minutes, it isn't a cause for concern. This is because the odor is simply the dust that has collected in the duct system burning off.

However, if you still notice the smell of burning dust several minutes or even hours after the furnace has been running, it could be a cause for concern. Luckily, all you have to do is check the air filter to remedy the problem. If the filter is very dirty or simply old, replace it.  

If this isn't the issue, you may need to have your duct system cleaned by a professional. While the system is being cleaned, ask for the technician to look for other possible causes of the burning smell, such as a faulty blower.

From the smell of rotten eggs to a burning dust odor that won't seem to go away, there are several common odors associated with your HVAC system that you should never ignore. For more information or assistance, contact resources like Kohl Heating & Air Conditioning.