Why Does My AC Smells Musty? Reasons and Solutions
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Switching the AC on during the hot and humid summer is equivalent to heaven in my books, especially when powered with solar energy! But what happens when your beloved air conditioning system smells…weird? Like this musty, rotten wood smell. While you may not turn off the AC, the smell can be gut-wrenching.
If you notice a smell coming from the AC, you may have mold growing inside the system or air ducts. You have to identify this musty smell and eliminate it, as it can be a potential health hazard and cause breathing problems.
Let’s look at the common reasons behind the AC’s musty smells and easy fixes.
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Why Does My AC Smell Musty?
There are many reasons why your AC may smell funky as soon as you turn it on. This musty smell is also known as ‘dirty sock syndrome.’ The sooner you find the reason, the sooner you can sort it out and get back to enjoying a cooled home!
#1- Dirty Evaporator Coils
Dirty or frozen evaporator coils are one of the common reasons why your AC smells musty and damp. It eventually becomes a breeding ground for mold growth, which is something you definitely don’t want! The dirt also builds up and is blown out when you put your AC on, which contributes to that damp, musty smell.
#2- Mildew/Mold in the Air Vents and Ducts
Mold and mildew growth is usually the main reason for that musty smell. Mold and mildew grow by spreading spores and having lots of moisture to work with. During the growth and reproduction stage, mold product gasses are called microbial volatile organic compounds (MVOC). These gasses usually have no smell, but some give off a musty, old smell. This means the mold and mildew growth have been left too long, causing the smell.
#3- Your AC Is the Wrong Size
The size of your AC depends on the size of your room or office. This is to ensure that the space is kept cool and fresh whenever you have the AC on. However, if you have an AC that’s too big, it will take out the fresh air too quickly and prevent it from being dehumidified. A unit that is too small does not provide any cooling effect, which also leads to an unpleasant smell.
#4- Blocked AC Drain Line
The AC drain line is a small dripping line made of PVC pipe that is found outside of your house, where the AC unit is. The drain lime removes condensation from the AC’s evaporator coil and keeps the room fresh and dry.
If the drain line is blocked/clogged, the AC will not be able to dehumidify your home properly, which causes a musty smell.
#5- Dirty, Blocked Filters
When the AC filters are dirty and clogged, the AC unit will not give off fresh and cool air. The filters should be changed regularly, as they will harbor bacteria and mold growth, causing an unpleasant smell.
#6- Air Ducts are Leaking or Punctured
If the air ducts are leaking, moisture will seep into the unit and is more likely to grow mold and mildew. This humidity causes growth, which contributes to the musty smell. This is a problem that is usually not spotted by the homeowner, so you have to get a team to identify the problem as soon as you get a smell.
#7- Drain Pan is Full
A full drain pan is basically stagnant water, which leads to an awful odor, making your AC smell unfresh. Keep an eye on the drain pan and empty it regularly.
Solutions to the Musty Smell Coming from the AC
No one wants their home smelling like dirty socks! Luckily, there are easy methods to get rid of that unpleasant smell from the AC.
Clean the Air Ducts
Over time of using your AC, the ducts can catch and accumulate dirt from the air, causing weird smells and inconsistent airflow. Leaving your air ducts can even increase the chance of rodent infestations! This doesn’t really have a DIY method, so I advise you to call a qualified technician to clean the ducts. It is suggested to do this every 3 to 5 years.
However, you can reduce smells by adding some baking soda inside the air ducts. Baking soda absorbs foul smells before it even gets to you, and deodorizes the air, so your home smells fresh. Make sure the air ducts are clean before doing this!
Change the Air Filters
A clogged air filter causes a nasty smell in your home. When getting an AC, you should be aware of how often the air filters should be cleaned or changed. If left for too long, it can cause the accumulation of mold spores, bacteria, and debris in the AC ducts.
Changing or cleaning your air filter can eliminate harmful particles, so the AC can circulate fresh air constantly. According to experts, air filters should be changed every 1 to 3 months. Your filters should be changed more frequently if you have pets, maybe every 2 months.
If you change the filters and still get that smell, you can upgrade your filter to a higher MERV rating. This rating shows how effective the filter is at preventing harmful particles.
Air filters with a high MERV rating can effectively trap mold spores, which cause musty smells.
Drain the AC Drain Line
Extra condensation collects on the evaporator coil and is drained through the condensate line into the pan. However, when the drain is blocked, the water is left standing, which promotes mold growth. This has an easy fix, though!
If you have a wet/dry vacuum, you can suck up any standing water and clear the drain line. If this does not seem to work, then you may need to bring in the pros!
Clean the Coils
The coils are important for heat conversation, so they are important to keep clean. When they are dirty, they can cause a smelly problem! You should clean your coils at least once a year to prevent allergens, as well as reduce energy consumption. Did you know that not cleaning your coils can increase your AC’s energy consumption by 30%? Yikes!
To clean your coils, make 10% of bleach and water spray. This is enough to kill the mold without harming the coils. You have to dilute the bleach as undiluted can corrode the metal in the AC. You can also opt for a coil cleaner if you have one on hand.
Remove the panel on the back of your AC, and you will see the metal fins, which are in front of the coils. Clean the metal fins using your vacuum. Then, spray the coils with your cleaning spray and wipe them. Once everything is dry, put the panel back and switch your AC on to check if the smell is finally gone.
Is The Musty Smell Dangerous?
While it is not an immediate threat that can harm you and your family’s health, it can cause long-term health risks if you do not sort it out quickly and properly. Mold in your AC can become a huge problem because the AC will circulate the spores throughout the home, which will make it an irritant.
Family members with various respiratory diseases and breathing issues will not deal with the musty smell, as their condition may get worse. You may also experience allergic-type symptoms when you are exposed to mold, and long-term exposure may lead to lots of doctor’s visits!
By keeping an eye on your AC unit during the warmer months, you can easily prevent this problem from becoming bigger than it needs to be. Apart from doing the DIY methods, you should also hire a professional to perform a routine check-up and maintenance on your AC to ensure that there is no chance of mold growth.
Frequently Asked Questions
How does mold even get in my AC?
Mold spores travel in the air until they settle in a favorable environment to grow and reproduce. Mold loves to grow where there are warmth, darkness, moisture, and nutrients. Your AC unit or drain pipes provide exactly this, so the mold grows and produces a musty smell. Mold must be sorted out immediately as it is a health hazard and can damage your AC.
Why does my AC smell after it rains?
After heavy rain, there is a chance of moisture building inside the air ducts and vents, which causes a musty smell. The moisture also facilitates the growth of mold and mildew, which also releases an unpleasant odor.
Why is my car AC smelling weird?
As you use your car AC, bacteria can grow in the AC’s evaporator, where moisture builds up. If left for too long, a mildew/mold smell can get into the car whenever you switch the AC on.
How often is AC maintenance needed?
You should get your AC maintained about two times a year. Experts usually recommend this to be done once in the spring and once in the fall. This is to ensure that there is no excess moisture, everything is clean, and the parts are all working well. Having your AC serviced also ensures that it is not consuming more energy than it needs to!