How Your Air Conditioner Can Make You Sick

May 28, 2015

Your home’s AC might not be the first thing you think to blame for that persistent headache, unexplainable drowsiness, or annoying cough. But think again.  

Your AC could be promoting mold growth in your home. And indoor exposure to mold, according to the Center of Disease Control and Prevention, is linked to a variety of health effects.
 
Mold grows where there is moisture. And there are more than a few ways your AC could be creating an unhealthy amount of moisture in your home.
 
In this article we’ll explain:

  • How high humidity promotes mold growth
  • Common AC problems related to mold growth
  • Ways to prevent and correct these issues

How high humidity leads to mold growth

The key to mold control is moisture control. Molds reproduce by means of tiny spores; the spores are invisible to the naked eye and float through outdoor and indoor air. Mold may begin growing indoors when mold spores land on surfaces that are moist. 
 
Ideally, the humidity level in your home’s air should never reach above 50% to prevent your air from being pushed into the mold-growing range of relative humidity. 
 
And some common AC problems can lead to high humidity in your home. Let’s look at 3 of them...

3 common AC problems related to mold growth

Oversized AC

Bigger is NOT always better when it comes to air conditioners. Especially when it comes to dehumidifying your home. 

Here’s why: A properly sized AC is will do 2 things for your home’s air– cool it down and remove humidity. 
 
To remove humidity, the AC has to run for a longer period of time. Oversized air conditioners run for a shorter time they cool your home’s air too quickly, which triggers your AC to shut off before removing the humidity.
 
In short: If your AC is oversized, you are at higher risk for mold and bacteria growth due to higher humidity levels.
 
Hint: If your AC runs for 10 to 15 minutes or less per cycle on a hot day your AC may be too big for your home.

Thermostat fan is set to “ON”

When your thermostat’s fan setting is switched to ON instead of AUTO, the fan continuously blows even when your system is not in the cooling process.  

This causes the buildup of moisture on your cold evaporator coil to get cycled back into your home—spiking humidity levels as a result.
 
The constant condensation and cycling of humid air also makes for a good breeding ground for mold on your evaporator coil.
 
Read more about the AUTO vs ON fan setting
 
In short: The air that blows over your inside unit’s evaporator coil in order to be cooled is blown back into your home. So, you’ll want to make sure it isn't being tainted by mold or stagnant moisture.

Condensate drain problem

Because your AC does create a fair amount of moisture within your inside unit, your system has a way to rid this moisture through something called a condensate drain line.  

When this drain or pipe is clogged, water can overflow into your home. The water (and usually very dirty water) leaking inside your home is a perfect recipe for mold growth in your home (not to mention some serious electrical issues, too). 

Tips for prevention and correction

  • Make sure your AC is properly sized. You can have a trusted air conditioning contractor perform a heat load calculation to make sure.
  • Leave your thermostat set to AUTO, rather than ON
  • Don’t ignore any sign of excess moisture inside your home, especially visible leaks in your home’s roof or walls.
  • Ultraviolet lights are one of the best ways to keep bacteria from growing inside of your air conditioner.

Pregnant women, infants, young children, the elderly and those with respiratory issues or sensitive immune systems, are at higher risk if exposed to mold. 
 
If you think high humidity may be a problem within your AC system and want to take steps to prevent mold growth, contact Santa Fe today
 
Santa Fe serves homeowners and businesses throughout the Kansas City metro area.