Your HVAC system is meant to keep your home comfortable and your indoor air clean. Even with regular maintenance to maximize the life expectancy and efficiency of your HVAC system, malfunctions can still occur.

A weird smell from the air conditioner is a clear sign of HVAC system malfunctions, so it’s important to know what the different odors coming from your AC might mean. It’s an issue that should never be overlooked, and homeowners need to understand what steps to take if they encounter such smells.

An odor problem doesn’t always mean costly repairs; it might simply be a dirty air filter or condensation that has led to mold growth in the unit. It’s important to pay attention to your other senses as well when you’re troubleshooting the smell – is there noise or fluids on the floor?

In this article, you will learn why AC smells weird and what to do about it.
 

Causes of Weird Smell Coming From AC

A weird smell coming from your AC could be caused by several factors:

1. Mold or mildew. Moisture can build up in the AC unit, providing a breeding ground for mold and mildew. These can emit a musty or damp odor.

2. Dirty air filters. If the air filters are clogged or dirty, they can trap odors and spread them throughout the room when the AC is running.

3. Clogged drain line. A clogged drain line can cause water to accumulate and stagnate, leading to a foul odor.

4. Dead animals or pests. Sometimes animals or insects can find their way into the AC ducts or unit and die, causing a strong odor.

5. Chemical smells. If your AC uses certain chemicals like refrigerants, a leak or malfunction could release odors that smell unusual or chemical-like.

6. Electrical or mechanical issues. Electrical problems or overheating components can sometimes produce a burning smell.

7. Outside odors. If your AC unit draws in air from the outside, it could pull in odors from nearby sources such as garbage, plants, or pollution.

To address the issue, it’s best to start by checking and changing the air filters regularly. You may also want to inspect the AC unit for visible mold or mildew and clean it thoroughly. If the smell persists or is particularly strong, it’s advisable to have a professional HVAC technician inspect the unit to identify and fix any underlying issues.
 

What to Do for an Electrical Smell?

Such a weird smell from the air conditioner as the smell of burning electricity is quite common. If your HVAC unit emits an odor suggesting it might be overheating, it likely is. Turn off your unit before attempting to diagnose the problem.

Electrical odors can have a variety of causes. For instance, there might be faulty wiring in your air conditioner, or your motor could be burning out. You can also inspect your air filter to see if it is extremely dirty, as this can restrict airflow and cause the electric resistance heaters to overheat. If it’s not an air filter issue, make sure the electricity is turned off at the master switch.

 
This weird smell coming from the AC needs to be examined by a professional immediately as, like with any electrical problem, there is a risk of fire. Trying to repair it yourself could lead to serious injury.
 

What to Do For a Moldy or Musty Smell?

A weird smell from the air conditioner resembling mildew or mold is probably the most common ailment of HVAC systems. When the AC is operating, a significant amount of condensation forms within the unit. When the moisture doesn’t drain properly, it can escape into the ducts and cause mold. Locating the mold buildup and cleaning it up will resolve the issue.

An HVAC technician can efficiently address the issue and ensure it doesn’t happen again. To prevent mildew and moisture problems, repair all water leaks, improve drainage, schedule bi-annual HVAC tune-ups, and replace HVAC filters regularly. Additionally, if you have exposed earth in your crawlspace or basement, consider exploring options to cover the soil.

A good way to protect your home and HVAC system from mold and mildew is to use a dehumidifier to keep moisture in check.
 

What Should I Do if AC Smells Like Garbage When I Use It?

Another weird smell from the air conditioner is the smell of garbage. During the winter, small animals often seek shelter in HVAC systems. Unfortunately, some of these animals don’t make it through to spring. If you turn on your AC system and immediately notice a strong odor reminiscent of trash or garbage, it could indicate that an animal has died inside your HVAC system and needs to be removed.

If you suspect this is the case, turn off the air, open the windows, and contact pest control or a professional HVAC specialist for assistance.
 

What Should I Do if AC Gives Off the Odor of Dirty Socks?

One of the more distinctive (and unpleasant) odors that can emanate from an air conditioning system is reminiscent of dirty socks. This unpleasant smell, often encountered when first using the AC after a long period, is quite common. As the name suggests, it has a musty odor similar to that of a gym locker room. Over time, when the air conditioner is not in use, mold, and bacteria can accumulate on the evaporator coil or other parts of the HVAC system.

Your first line of defense against this buildup of mold and bacteria is your air filters. If the musty smell persists, start by cleaning or replacing the filters.

Should the smell linger even after regular use, it is recommended to have your evaporator coil professionally cleaned. This is particularly important for individuals with asthma or allergies, as mold spores and bacteria in the air can exacerbate their conditions. Additional steps you can take include:

• Checking and replacing your filters
• Cleaning the drain pan
• Inspecting your ductwork

While these tasks can be accomplished by homeowners, it’s best to contact a professional.

Remember that a weird smell from the air conditioner like dirty socks is not a danger.
 

What if You Smell Rotten Eggs or Gas?

A weird smell coming from the AC that looks like rotten eggs should alert you. This is one of the most dangerous smells when it comes to an HVAC system, as it means you’re probably experiencing a natural gas leak. As natural gas is odorless, utility companies have added the scent of rotten eggs to the gas supply to help warn of possible gas leaks.

Provided there aren’t any rotten eggs in your home, the smell of rotten eggs or sulfur most likely indicates a natural gas leak. Don’t take this lightly. Open the windows in your home and get out. Then contact an HVAC professional for immediate assistance. However, when you turn on your furnace, you might notice an odor that smells like burning gas. This typically happens when your system has been inactive for an extended period. During the summer, dust accumulates within the HVAC system on the heat exchanger. When the furnace is turned back on, the dust gets burned off. Give it a few minutes and the smell should fade away as the dust decreases.
 

Advice on What to Do if Your Air Conditioner Smells Strange

A common reason that many HVAC units create more odors is that houses are often built without the necessary ventilation. This results in the unit running out of air needed for combustion. This is one of the main causes of foul HVAC odors for many homeowners, which raises concerns about indoor air quality.

Be sure to replace the air filter regularly and have your system inspected by a professional at least once a year. If you notice that your AC smells weird it’s best to call a professional to make sure it’s not something serious. McMillin Air can help you with any issue you could be having with your HVAC system, give us a call at 623-432-5202.