On a muggy day, there’s nothing quite as beautiful as walking into an air-conditioned home. Upon entering, one will immediately notice the cooler temperatures and lack of humidity. 

An inspection of an AC system will reveal the presence of a condensate pan located just under the evaporator coils. Air has to pass over these coils to be cooled, so one may ask: Does air conditioning reduce humidity?

Humidity is a quantity representing the amount of water vapor in the air.

But First – How is Cooling Achieved?

HVAC systems achieve heating and cooling by moving air through parts of the system to raise or lower the temperature. Temperature reduction happens as the air passes through evaporator coils. These coils contain refrigerants that will pull the heat from the air. 

The process effectively lowers the temperature of the atmosphere. Along with the heat, evaporator coils will remove moisture from the air, which is why there is a condensate pan underneath the evaporator coils.

How Does This Remove Moisture?

As air is cooled, moisture clings to the coils, which tells us that air conditioners reduce humidity. Humidity is a quantity representing the amount of water vapor in the air. Water vapor is simply water in gas form when it cools it will return to a liquid form.

As warm air passes over the cold evaporator coils, the temperature reduction will cause water vapor to return to its liquid state through the process of condensation. This liquid water will cling to the coils instead of the air as it passes through; this is how air conditioners reduce humidity.

Why is Removing Moisture Important?

Reducing humidity is a desirable function of an air conditioner but is also crucial to the systems function. Humid air is harder to cool as it will retain heat, making it much more challenging to cool. If the atmosphere is moist, the air conditioner will have to work harder to cool the air and raise energy bills.

Keep the Coils Clean

Because the coils collect moisture from the air, corrosion is a natural obstacle that the system will face. The upkeep of the system warrants regular cleaning and inspection of the coils to ensure they are functioning correctly; this is a step that homeowners can take themselves but will also want to make sure it is a part of regular maintenance plans.

Do I Still Need a Dehumidifier?

Just because an air conditioner reduces humidity does not mean it won’t benefit the system to run a dehumidifier. In particularly humid regions, a dehumidifier is a desirable addition to an HVAC system. 

By reducing humidity levels, one will reduce the strain placed on an air conditioner as air with low humidity levels is less challenging to cool. 

Reduction of humidity will also slow the corrosion of evaporator coils, ductwork, and other parts that may collect condensation, meaning a dehumidifier can also aid in extending the life of the system.

Humidity Level Risks

High humidity levels are not only a strain on the HVAC system. It can cause havoc all over the home. Over time, the humidity will cause wallpaper to peel and wood to warp. It also contributes to how often one spends time cleaning surfaces throughout the home. Because a home dehumidifier makes the home more comfortable and provides additional protection, it is an expense many are happy to make.  

Proper Thermostat Settings 

It’s not uncommon for an air-conditioned home to still feel humid at times; this comes down to the thermostats setting. An AC thermostat fan typically has two settings: On and Auto. If set to “on,” one may still have high humidity levels even if temperatures are lowering. 

Why is this? If the air is always blowing over the coils, there is not enough time for the moisture to condensate as it passes over the coils.

No matter the fan setting, condensation will be present on the coils. Time is needed for the liquid water to collect and drip down into the condensate pan beneath. As air flows over the coils, if enough condensation is already present, it will remain in the air instead of clinging to the coils.

The “auto” setting is more desirable when humidity is an issue. The system will cycle the fan, giving the condensed water enough time to collect in the condensate pan and remove more water from the air. The “auto” setting will also reduce strain on the system, and because it isn’t continually running, less energy is required, making it a much more cost-effective than merely leaving the fan on. 

Concluding Thoughts: 

An air conditioning system’s ability to remove water vapor from the air is critical for indoor air quality, the life of the system, and comfort. Without this function, the system would have to work much harder and cost homeowners more money in energy bills.