Why Your AC Smells Musty

ac smells musty

In places like Florida that are notorious for their heat, having a functional air conditioner is the quintessential feature of indoor comfort. You may melt into a puddle of sweat between the time you park your car and when you unlock the door to your house, but once inside, all is supposed to be well. But what happens when you’re met not with crisp, refrigerated air but with the smell of dirty socks? If your AC unit is blowing musty or unpleasant air throughout your house, it may be because of serious underlying issues. Learn what is causing your AC to stink and what you can do to fix it.

5 Reasons Your AC Smells Musty & How to Fix it

1. Dirty or Clogged Filters

Dirty air filters can cause numerous problems in an air conditioning system. They are responsible not only for keeping pollutants out of indoor air circulation, but also ensuring proper airflow throughout the unit. Clogged air filters can lead to huge performance problems, restricting airflow and causing your unit to work harder for a lesser result. If a buildup of moisture develops on an air filter, the rancid smell will undoubtedly blow throughout your home.

How to Fix Dirty Air Filters

Though the specific needs of your AC unit will vary, the general wisdom is to change filters at least every 90 days. If your AC unit is producing bad smells or performing poorly, checking the air filter is always a good place to start. If it is clogged or dirty, replace it as soon as possible. This is an easy fix and can be done yourself, but if you suspect other problems at play in addition to a clogged filter, calling a professional technician is probably your best bet.

2. Clogged Condensate Drain Lines

The condensate drain lines in your air conditioner are meant to remove water from the unit when the evaporator turns refrigerant liquid into gas. This is an essential piece of the heat-exchange process, but malfunctions and wear and tear can cause mold, algae, or other debris to develop along the condensate lines.

How to Fix Clogged Drain Lines

Clogs in your drain line can often be resolved without the help of a technician if you’re willing to put in the effort. By clearing external debris and running a cleaning agent (such as vinegar, hot water, peroxide, or bleach) through the drain opening, you can remove most blockages. For minor clogs, you can even try running a garden hose or a long plumbing snake through the top of the drain pipe. Just be sure that your air conditioner is turned off at both the breaker and the thermostat before attempting the repair.

If you suspect a clogged drain pipe is causing your AC to smell, refer to our step-by-step guide for how to unclog your drain pipe: How to Unclog Your AC Drain Line With Vinegar

3. Dirty Evaporator Coil

The primary task of evaporator coils is to remove heat from the indoor air. Refrigerant is then converted from a liquid into a gas and the new, cool air is blown throughout your home. If — due to some AC malfunction or lapse in maintenance — too much moisture accrues on the evaporator coils, your AC unit will not function well, and mold and mildew can develop.

How to Fix Dirty Evaporator Coils

Evaporator coils are found in the indoor portion of your AC unit, located either inside or next to your air handler. They are often covered by an access panel, which can be loosened or removed with a screwdriver. Once you’ve located the evaporator coils, you can use either a coil cleaning brush or a mixture of mild detergent and water to remove any buildup.

Read: How to Clean AC Coils

4. Air Duct Problems

Leaks in your ductwork can let in dirt and humid air, which creates a ripe environment for mold growth. If mold infiltrates your ductwork, it will spread sour odors throughout your home. Moreover, leaky AC ducts will prevent your air conditioner from cooling properly. If you find that your unit is running for long periods of time but not cooling, it may be due to leaky ducts.

How to Fix Air Duct Problems

Duct cleaning is best left to a professional HVAC technician. They can clean your ducts as well as seal them, protecting them against future leaks. They can also inspect the rest of your AC system to make sure there are no other problems to resolve.

5. Clogged Drain Pan

If your AC drain line isn’t working properly, water may build up in the drain pan. This standing, stagnant water can lead to fungal growth if it is not cleaned.

How to Fix a Clogged Drain Pan

Removing the stagnant water is only the first step in cleaning a clogged drain pan. You should also clean it with vinegar, bleach, or another cleaner capable of killing bacteria and mold. Since the drain pan itself is probably not the issue, you will likely have to clean out your drain line, following the steps outlined above.

Prevention and Maintenance for a Musty AC

While some of the causes for a musty AC can be fixed at home, it is never a bad idea to call a licensed technician for any of these problems. Several AC components are easily damaged, and there may be surrounding issues even an expert DIYer can miss.

You may also consider preventative steps like investing in indoor air quality devices such as UV filtration to keep the chances of mold and bacteria growth at a minimum inside your air conditioner. Changing filters and having AC tuneups regularly will also go a long way in preventing any of the problems mentioned above.

AC Service in Brevard County

At Colman Air, we understand that sometimes, AC issues happen during the most inconvenient times. This is why we have a 24/7 AC emergency line. Call us if you need assistance ASAP, if you’d like to learn more about faulty capacitors, or to schedule routine HVAC maintenance.

24-HR Emergency Service: (321) 360-7566

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