When your air conditioner is working correctly, it both cools and removes moisture from your indoor air. However, there are multiple factors that can cause your air conditioner to fail at its “dehumidifying duties.”
If your home feels muggy even while the air conditioner is running, one of the reasons below could be why.
1. The thermostat is on the wrong setting.
Before calling your trusted HVAC contractor, check your thermostat settings. Make sure your system is set to “AUTO,” and no “ON.” When the setting is “ON,” your system’s fan is going to run continuously, even if the air conditioner isn’t actively cooling and dehumidifying the air. Basically, the system is just circulating air throughout your home. When the setting is “AUTO,” your system will cool and dehumidify air whenever the fan is running.
2. Dust and dirt are disrupting your air conditioner.
Your system’s air filter can only do so much. If enough time goes by without preventative maintenance, dust and dirt will accumulate on both your indoor and outdoor air conditioner coils. Dust on the outdoor coils inhibits your air conditioner’s ability to disperse heat into the outdoors, which, in turn, interferes with the refrigerant cycle as a whole. A disrupted refrigerant cycle makes it harder for your air conditioner to dehumidify air and perform efficiently.
3. Your indoor AC unit’s evaporator coil is frozen.
Your air conditioner’s indoor unit contains the evaporator coil. The evaporator coil removes heat and humidity from your indoor air. If something is blocking airflow through your system (like a dust-clogged air filter), or if there’s not enough refrigerant flowing through the evaporator coil, a layer of ice or frost can form over the coil. When this happens, the coil can no longer extract heat or humidity from your home’s air.
4. Your current system isn’t the right size for your home.
It’s essential that your air conditioning system not be too big or too small for your home. If the system is too big, it’s only going to run for extremely short cycles, which can result in uneven temperatures throughout your home. If the system is too small, it’s going to struggle to cool and dehumidify your home no matter how much it runs.
5. Your current system is getting close to retirement.
Has the air in your home gotten muggier in recent years? According to the National Association of Home Builders, air conditioners last 10 to 15 years, so if your AC system is over 10 years old, then you can bet the humidity problem is an aging air conditioner. When shopping for a replacement, make sure you involve a licensed HVAC professional that can help you choose an appropriately-sized system for your home so that you can avoid problems like the one mentioned above in #4.
6. Your ductwork has leaks.
Ductwork typically “lives” in humid, unconditioned areas, like attics and crawl spaces. As it ages, it can form rips and gaps that allow moisture to mix with your conditioned air. You can also have this problem in relatively new ductwork that wasn’t connected or sealed properly.
7. It’s just really, really humid out.
Right before stormy weather, the air outdoors becomes excessively humid, and even a decent air conditioner in good condition might not be able to keep up. You can help your AC out by keeping all of the windows closed and running your kitchen and bathroom exhaust fans when either of those rooms is in use for cooking, showering, or bathing.
If the humidity is so high in your home that it’s creating problems, like mold growth or physical discomfort, you can also install a whole-home dehumidifier. These devices regulate your home’s indoor humidity and keep it at your desired level.