Should You Run AC Fan Only?

An AC fan-only setup can be a viable option in certain circumstances. In this setup, the fan will constantly blow air, regardless of whether your AC is on or off. If you need all-around comfort and cleaner air quality, the “always-on” option would certainly help. But do note that this will increase your electricity bills.

There are tons of good reasons why most AC users set their thermostat settings to “auto.” But in certain circumstances, a fan-only setup is a better option. When is the right time to go auto-mode or fan-only? Let’s find out more about using the fan-mode-only option in this blog. 

Should You Run On AC Fan Only?

Both options have their pros and cons, and users should weigh the best option for their case. If your primary concern is having a consistent temperature and cleaner indoor air, an AC-fan setup will largely help. However, setting your AC fan to auto is a more viable option if you aim to save money.

What Is Fan Only Mode On The Air Conditioner?

A fan-only mode is the option wherein the AC fan is constantly running. The fan continues to operate, regardless of whatever setting is for the heating or cooling system. This setting is similar to using a normal fan, but the component is a part of (and can be used with) the air conditioning unit. 

Fan mode doesn’t cool the air because the compressor is not functioning with it. The air circulates the room and is not being cooled or heated. But because the compressor is not functioning, the whole system uses less energy in a shorter period. The AC fan stops or starts depending on the settings from the thermostat.

Should The Fan Be On When The AC Is On?

The AC fan can operate alongside the air conditioning unit. Its main purpose is to circulate the AC’s output into the designated area with more efficiency. Although it seems counterproductive, this method will help you save a lot on electric bills. Using the fan with the air conditioning unit will only yield good results if you know how to set things properly. 

Fortunately, getting the optional settings is quite an easy step. 

One of the best tricks in running the fan alongside the AC is to keep the thermostat settings closer to the outside temperature. This trick works because the running fan can bring additional cooling of at least four degrees.

For example, if the temperature outside is 75, set your thermostat option to 71. No additional setting is needed. The fan will help fill up the four-degree gap. 

Should I Set A Minimum Fan Runtime?

If you’re running the AC fan throughout your home, you must consider whether the area’s humidity is too high or too low. For users who are in hotter locations, setting the minimum fan runtime to longer durations is recommended. On the other hand, if you’re living in a colder region, a shorter runtime might benefit you more.  

Meanwhile, if the user plans to use the “always-on” mode, the alternative course of action is to slow down the fan’s speed. Not all ACs have this option, so check your unit’s manual on how to slow down your fan. Most modern ACs have a programmable interface, wherein you can automatically set the fan speed at certain times of the day.

Does Running The AC Fan Use A Lot Of Electricity?

Unfortunately, running the AC fans non-stop will likely increase your electricity bill. The reason for this increase is the fan itself. Some AC units don’t have a fan designed for continuous usage. Most AC fans are designed for usage alongside the AC itself. Hence, a typical AC fan doesn’t have high energy-saving features. 

Running the fan with lower settings in a constant mode can rack up electricity consumption. This is compared to short AC bursts that automatically stop once the thermostat detects the right temperature. The automatic mode saves at least $25 to $50 per month or more than $300 annual savings. 

The difference in electricity usage is due to the wattage consumed each day. Smaller yet prolonged electric usage tends to accumulate more expenses due to power inefficiencies.

Does Running The AC Fan Reduce Humidity?

AC fans do not reduce the humidity inside your home due to one reason: trapped moisture. Most AC users don’t realize that their units do two things in the air: cools/heats it and remove its moisture content. This is the reason why the air is always dehumidified when you’re running the air conditioning unit. 

Indoor air is cooled down using a component known as the evaporator coil. This coil carries refrigerant around, which cools down the air passing through. Another thing that the refrigerant does is to remove the condensed moisture in the air being processed.

Does AC Fan Bring In Outside Air?

The short answer is: it depends on the type of air conditioning unit installed. Most residential AC units recirculate the air around the designated indoor area. There is no fresh air that comes to the room or the whole indoor structure. The fan also uses the same method when circulating the air around the house. 

However, some ACs can draw in outdoor air when certain conditions are met. These types of ACs are usually used on commercial or public buildings, wherein an economizer gets installed. If the air outside is colder inside, or if other conditions are met, the economizer draws the air outside, wherein the fan recirculates it in the room.

Disadvantages Of Running AC Fan Only

Running the AC fan in the “always-on” mode is not always beneficial at all times. You can face some disadvantages in running your AC fan non-stop. If you’re preparing to get a fan-only system, you should tackle the following disadvantages. 

Higher Electricity Bill

There’s a high price to pay when you want to have consistent cooling in your area. And that high price tag is usually in the electric bill. If you don’t mind paying a high electricity bill, then you can leave your AC fan in “On” mode for an extended period. 

Frequent Filter Replacement

Another headache that you need to tackle is the frequent replacement of air filters. There are AC users that leave the fan on to avoid allergies by keeping the air constantly clean. However, the filters that clean them should be replaced regularly to keep allergen-free air at all times. 

Hot Ducts Can Reintroduce Warm Air

Residential ACs don’t usually suck the air from the outside to cool down the indoor area. One reason why a room with AC is sealed is to avoid introducing warmer air to the system. Unfortunately, this can still happen via the AC ducts. If the outside temperature heats the ducts, your fan will recirculate warm air instead since the compressor isn’t working. 

Cold Air Is Recirculated During The Winter

And this same thing happens during the winter as well. When the ducts outside became cold enough, and the heater is not running, the air passing through it will cool down. Since the fan only circulates the air around, the cooled-down air will lower the area’s temperature.

When Running The AC, Should The Fan Be On “Auto” or “On”?

It depends on whether you or anyone else will use the area. The AC is still usable regardless if the fan is on auto or always-on mode. Using the fan in combination with the AC can save money if you know how to tinker with the correct settings. 

Can You Leave The AC Fan On All Night?

If you don’t mind sleeping in a heavily humidified room, you can leave the AC fans during the evening. However, this setting might be a tad bit uncomfortable. If you don’t want to use the AC at night, a ceiling fan might be a better option than an AC fan.

Running AC Fan-Only With Windows Open

You can run your AC fan with windows open during the spring. The comfortable spring temperature will circulate all over the house, which can cool down hot spaces. Running an AC during the spring might be overkill since the temperature is not that hot. In this case, the fan-only option offers a better value without sacrificing comfort.


Both the “Auto” mode and the “Always-On” mode can be helpful in different circumstances. The choice should be dependent on the user’s needs and location. The “always-on” option is great if you want an evenly-distributed air temperature inside your home or in the designated working area. But this option is less efficient in energy consumption and doesn’t reduce the humidity. 

The Auto mode, on the other hand, is used when the programmed thermostat settings are followed. This method can save you hundreds of dollars per year or more, depending on the programmed operating hours per day. However, this option can only cool down a few rooms and areas. And these areas are only cool for a few hours a day.