Musty Smells Coming From Your AC Vents? An Oklahoma Pro Explains

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HVAC tech repairing AC unit in Edmond, OK

Whenever your AC clicks on, the air from your vents comes with a musty odor. Sound familiar? Now, the real question is, “What’s causing that smell”?

Mold and/or mildew are more than likely the main culprits behind the smell. This is not good because not only is your AC venting a bad odor, it’s distributing either mold and/or mildew spores throughout your house, which you and your family are breathing in. 

The reason for this mold/mildew build-up can stem from several issues in your AC unit including:

  • A dirty evaporator coil
  • A full drain pan
  • A clogged condensate drain line

In this blog, we’ll go through each of these AC issues, including how they can create mold/mildew over time and how they can be fixed.

Need an AC repair professional? We’ve got you covered.

Possible problem# 1: A dirty evaporator coil

The evaporator coil in your AC system has the potential to provide all 3 factors that bacteria, mold and mildew need to thrive:

  1. Moisture
  2. Darkness
  3. Warm temperatures

Now, all three factors are typically only present when your system is quickly switching between heating and cooling. The heat plus the moisture produced by your evaporator coil in the darkness of your indoor unit (where the coil is located), is the perfect storm for a dirty, smelly evaporator coil.

That said, if it’s a time of year where you’re running the heat in the morning/night but the AC during the day, this is likely your issue.

The fix: To get rid of the smell and stop the mold/bacteria growth once and for all, it’s strongly advised that you have your coils thoroughly cleaned by a professional. To prevent a dirty evaporator coil in the future, we suggest getting regular AC maintenance. Most professionals will check and/or clean your evaporator coil during a routine maintenance visit.

Additionally, if you wish to maintain the coils (after a professional cleaning), you should consider having a pro install a UV light next to your coils as well. UV light can prevent any further growth of mold/mildew in that area.

Possible problem #2: A damaged/rusted drain pan

Your AC removes humidity from the air as it cools. The evaporator coil is what extracts that moisture (humidity) from the air. As the evaporator coil strips humidity from the air, moisture collects on the coil and eventually drips down into a drain pan (a pan that sits underneath your indoor ac unit). 

After being used for a long period of time and going through typical wear and tear, the drain pan can eventually become rusted or worn out. A rusted/damaged pan means water can leak from the pan onto the surrounding floor, insulation and other surrounding objects, and that moisture can lead to mold/mildew.

The fix: You can try replacing the drain pan on your own, but be aware that changing it yourself can be quite a difficult process, so we strongly recommend calling an HVAC pro who can have it taken care of for you.

Possible problem #3: A clogged condensate drain line

If you begin to notice that your AC is randomly shutting off shortly after turning on or you see a large amount of water pooling up around the inside unit, it means your AC’s drain line is clogged and is the root of the problem. 

You see, as your air conditioner works/cools, it removes humidity from the air and the moisture is sent to the drain pan where it’s then drained outside via the AC’s condensate drain line. The problem is, if that drain somehow becomes clogged, the water can back up. As the water just sits, it not only attracts mold/mildew and bad odors, but it can eventually cause expensive water damage.

The fix: Simply clean/clear the condensate drain line. This can be done yourself by pushing a stiff, thin wire brush into the end of the drain line and using a shop vac or special pump to suck out any remaining debris and clear the clog.     

Pour a cup of bleach into the access opening in the drain line near the AC unit to kill any algae, dirt, mold, or mildew that has built up inside the pipe. This will prevent any future clogs. 

On the other hand, if you don’t feel comfortable or well-equipped enough to clear it yourself, you can always call a professional.

Looking for an AC repair in Edmond? Look no further.

Here at Prudhom, we pride ourselves on working according to your immediate needs and never selling you on a repair you don’t actually need or want. Our technicians give you honest, upfront pricing on all AC repairs/services, and we’re so confident in our process, that we offer a 100% satisfaction guarantee.

Learn more about what we do and what to expect when you hire us by visiting our AC repair page.