When Your Home’s AC Isn’t Controlling Humidity in San Antonio

Couple Sitting Under Air Conditioner

When your home’s AC Is Cooling But Not Controlling Humidity

An air conditioner not controlling humidity in your home is a big deal. When you leave your home for a while and come back home, the first thing you’ll notice is the way your home smells. If you start noticing a “musty” smell when you first walk in, that’s an indication of humidity in your home. Normally, when you run an AC, the relative humidity should always go way down. But a musty smell is an indication of something going wrong. If this is the case in your house, you’d better act sooner than later.

Here are some signs that your AC is still running but failing to control the humidity in your home:

ac cooling but not removing humidity might cause condensation on the windows
Condensation on the windows is a tell-tale sign that your AC unit is cooling but also increasing humidity levels.

Example: Let’s say you have 82°F and 63% humidity. When you turn your home’s air conditioner on, you should see the temperature decrease to about 75°F and the humidity drop below 35%. If you see your air conditioning turned on however your home’s humidity staying at (60%) or even higher to 65%, 70%, and so on, something is definitely wrong. If your home’s thermostat doesn’t have a humidity meter built into it, we can install one very easily.

So what could be wrong with my AC unit if it’s cooling but not controlling my home’s humidity?

There are a few main explanations why the relative humidity going up while your A/C is turned on.

Reason One:
A properly working air conditioner always decreases indoor relative humidity levels in your home whether it’s a one story home or a two story home. If your AC is blowing cold air but its not removing humidity, your AC equipment has something mechanically wrong that is preventing the AC from performing its dehumidification functionality.

Dirty AC coils could be the culprit:
Humidity goes up when ac is on due to dirty coils and this is a very common cause in San Antonio Texas.
Indoor cold coils are responsible for moisture accumulation and removal via condensation management. If anything is wrong with these coils, you will see that cooling and especially dehumidification functions are impeded. The AC coils on your home’s INSIDE AC air handler need to be cleaned on a regular basis. During the summer in San Antonio, your home’s AC unit can run almost 24 hours a day and it moves a lot of air. During this time, your AC coils can get clogged and coated with all types of junk including mold, mildew, pet dander, human skin cells, dust and more. All of these things accumulate on your Air conditioning coils and form a slimy sludge that coating that prevents your AC unit from running efficiently and removing your home’s humidity by using condensation. Your AC coils really need to be cleaned quarterly during the summer and at least once every 6 months in Fall, Spring and winter to prevent dirty AC coils.

Air Conditioning Unit Is Too Big (Oversized AC Leads To Short Cycling).
This is another common culprit for humidity increasing while AC is running. If the AC is oversized, it will start to short cycle. You can read exactly what AC short cycling is here.

What this means that the refrigerant cycle doesn’t follow the whole cycle because your AC unit is so big that it reaches the set temperature too quickly but doesn’t have enough run time to extract humidity from your home’s inside air. This is why you should run from offers like “New AC Units For Just $6995” because you don’t want to buy an air conditioning system that not properly sized for your home.

When you have an HVAC unit that’s not properly sized and not removing your home’s humidity, you’ll see cold humid rooms in your home. This is usually the room where the indoor air handler is closely positioned (in the case of mini splits) or where a portable or window AC unit is located. AC will be able to lower temperature but unable to lower humidity levels.
You will also have hotter humid rooms – unbalanced hot spots where the AC seems to underperform. When AC is too big, its too massive cooling output might reach the set temperature (let’s say 72°F) in 1 room but will leave other rooms hotter. Your oversized Air conditioner turning on and off every few minutes. This is a tell-tale sign of a too big AC unit short cycling. If you think an oversized AC unit is causing cooling but not dehumidifying when turned on, the cleanest way is to install a smaller, properly sized ac system. Humidity can cause all kinds of problems with mold and mildew throughout your entire home and damage sheetrock, wood, flooring, carpeting, all of your air ducts and more – it’s definitely a good investment to trade your oversized unit for a properly sized HVAC unit.

Your Thermostat Settings can also cause humidity problems in your home. To Prevent humidity problems, make sure your thermostat is set on ‘Auto.’
It seems quite reasonable to start your AC unit on the ‘On’ setting. That means that AC is running, right? Truth is, the ‘On’ setting on an air conditioner tells the unit to run the indoor blower (only the fan) all the time. This is regardless if there is even a need for cooling or dehumidifying. If the fan is constantly running, it could release the condensed water from inside your AC ducts and on the indside AC coils back into your home. You will see this as AC cooling but not removing moisture. In fact, if the indoor coils are full of water, you will see humidity increasing while AC is on. You might even see water dripping from your AC vents in certain rooms – This is a huge sign af humidiy problems with your AC system. So definitely ensure that your home’s thermostat is set to “Auto” instead of “On.”

If your home has a musty smell due to high humidity, Call Caliente today!


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