Having air conditioning in your home is essential for keeping cool and comfortable, especially in the hot California summers. One thing many people don’t realize, though, is that central air conditioning systems can sometimes be prone to mold issues. Mold normally shouldn’t occur if the AC system is working properly, but it can happen due to issues like a dirty air filter or clogged condensate drain system.

If mold is present inside your AC system or anywhere else in your house, your air conditioning will then spread lots of mold spores into every room as it runs. Mold spores are a major issue in terms of indoor air quality and can create problems with breathing easily or even possibly make you sick. Mold is an especially big concern for people with preexisting respiratory issues like asthma or COPD and also for many people who suffer from allergies. In this article, we’ll explain the reasons that air conditioning can contribute to mold issues in your home and what steps you can take to overcome them.

Why Central AC Systems Are Prone to Mold Issues

The main reason that a central AC system can lead to mold growth is due to condensation. Condensation naturally occurs when warm, moist air meets a much cooler surface and the air cools down to its dew point. In fact, the air doesn’t even need to be that moist for condensation to form. That’s why even in a desert you’ll still end up with some condensation forming on a cold glass of water any time the air temperature is quite a bit warmer than the glass. The reason this happens is basically that the cold surface causes the temperature of the evaporated water molecules in the air to cool down to the point where they transform from a gas into a liquid.

This process happens naturally on the evaporator coil in an AC system as it runs since the refrigerant flowing through the coil is far colder than the air flowing over the coil. That’s how an AC system helps dry out the air in a home and keep it from being as humid. This condensation normally isn’t an issue since most of the water drips off the evaporator coil into the drain pan below it. The warm air flowing over the coil also helps dry it out. However, if the AC system has an issue that prevents it from having proper airflow, the coil can remain damp enough that mold may start growing.

A similar issue is that the ducts in your home are surrounded by air that is much warmer than the air your AC system puts out. This is why you may sometimes notice that some of your ducts “sweat” during the summer and have water dripping off them, and this water can also create the potential for mold growth. Ductwork condensation is an especially common issue in California where a large percentage of homes are built with a concrete slab foundation instead of having a crawl space or basement.

In homes with crawl space or basement foundations, most of the main supply ducts that carry the cold air from the AC system are located either in the crawl space or basement. This reduces the chances of condensation forming since crawl spaces and basements are below ground level and tend to stay fairly cool in the summer. In homes built on a concrete slab, the indoor part of the AC system and most of the supply ducts are usually located in the attic. This can be problematic since attics can get extremely hot during the summer due to all of the heat that’s absorbed by the roof. That means there is a much higher chance of condensation forming since there is a much greater difference in temperature between the inside and outside of the ducts.

How to Prevent and Overcome Mold Growth From Ductwork Condensation

The good news is that preventing condensation on your ducts that could lead to mold growth is fairly simple. All it usually takes is to insulate all of the ducts in the attic and other warmer parts of your home. Wrapping the ducts with insulation will shield them so that the hot air that surrounds them doesn’t come into contact with them, which mostly eliminates the possibility of condensation forming.

If you have ductwork in your attic, it also helps to ensure that the attic has proper ventilation. Ventilation allows the hot air that collects in the attic to escape up through the roof. This process then pulls cooler air in from outside so that the attic always stays around the same temperature as outside. The air in a poorly ventilated or unventilated attic will also end up being quite humid, which further increases the chances of condensation forming on the ducts.

How to Keep Your AC Evaporator Coil Free of Mold

Having a technician clean the evaporator coil in your AC system every year is important and something that is always done as part of a routine maintenance service. The only issue is that the mold, mildew and bacteria can eventually start to return once you start running your AC again. This not only creates issues with air quality but can also negatively impact AC efficiency. The reason is that the growth partially insulates the coil and prevents it from capturing as much heat out of the air flowing over it.

Coil cleaning helps prevent mold issues, but another effective option for overcoming and preventing mold growth on your AC evaporator coil is to install a coil-sanitizing UV light unit. All microorganisms like mold, mildew, bacteria and viruses are highly susceptible to damage from ultraviolet light. When the right wavelength of UV light shines on these microorganisms, it damages their DNA and essentially destroys them or makes it impossible for them to reproduce and spread.

This type of UV light unit is meant to be installed so that the UV rays shine directly on the evaporator coil. As soon as the unit is turned on, it will quickly eliminate any growth on the coil and prevent future mold growth. The unit stays on 24 hours a day for however long that you’re using your AC system so that you never have to worry about any mold issues. If the AC doesn’t run for 24 hours or so and the evaporator coil remains wet, mold may quickly start growing. This is why the light stays on so that mold can’t start growing in situations where the weather is cool enough that the AC system stays off for a prolonged period.

Mold can also grow in the drain pan or inside the condensate drain lines if your AC doesn’t drain properly. Luckily, these issues can also usually be prevented through annual AC maintenance. There are also fungicidal tablets that you can put into a drain pan to inhibit mold growth.

Since 2004, Huft Home Services has been providing reliable, trustworthy HVAC, plumbing and electrical services throughout the Sacramento, Elk Grove and Yuba City areas. As the area’s leading indoor air quality service, we can help you tackle any mold problems or other air quality issues in your home.

We install UV lights, dehumidifiers, humidifiers, air purifiers and more. We’re also ready to take care of your air conditioning and heating maintenance, repair and installation needs. To get more information or to schedule an appointment for any home service, contact our expert team today.

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