Fan Mode on AC: What Is It & when To Use It?

Fan Mode in AC is an air circulation feature on your air conditioner (AC) that sucks up the surrounding air and pushes it out through the blower fan. When in use, this feature turns off your AC’s compressor, leaving only the blower fan in use. 

The purpose for this feature is to keep the air in your home from feeling stagnant. The air also goes through the AC’s filter, which helps remove dust and impurities from it.  It is important to note, however, that with the compressor off, Fan Mode has a limited effect on cooling the air or reducing the humidity. And depending on your specific AC unit, you may even notice a limit to how much air circulation your fan feature provides:

  • Centralized ACs have the widest range, being strong enough to circulate the air in multiple rooms. 
  • Window ACs can be powerful enough to circulate the air in a large room, but unlike a centralized AC, its range is restricted to one room. 
  • Portable ACs may offer you the luxury of being moved into the spaces where they are needed, but portable AC fans are less powerful than those on a centralized AC unit or a window AC. They can circulate air in smaller rooms but are less effective in larger rooms. 

When to Use Fan Mode in AC

It is best to use Fan Mode in AC in the early morning and/or in the later evening. During these times, the weather is cooler and you will not feel uncomfortable without Cool Mode. 

The AC fan circulate mode will also benefit you throughout these circumstances:

  1. When you want to save energy and money. To reduce the amount of energy you use, you can turn on Fan Mode in place of Cool Mode. Because Fan Mode shuts off the compressor, your AC unit will require 85% less energy to run, saving you money on your monthly energy bill. Fan mode consumes as few as 60 watts to 150 watts while AC mode on a window AC uses 1,000 watts to 4,500 watts. 
  2. When you want to keep your AC from smelling musty. As the AC cools or dehumidifies, it sucks in the surrounding moisture and expels drier air. The moisture left in the machine will remain on the evaporator coil or in the drain pan, which can produce mold. To prevent mold, turn on the Fan Mode to speed up the moisture evaporation process. (Note: This is a preventative measure and does not get rid of any mold already inside your AC unit.)
  3. When you want to reduce allergens. Outside heat and inside stagnant air combine to worsen allergies. When Fan Mode is on, your AC pulls the surrounding air through an air filter inside the unit, reducing the pollutants in the room. 
  4. If you want to lengthen your AC unit’s lifespan. When using Fan Mode, the compressor is off, and the AC unit experiences less wear and tear over time. This gives it a longer lifespan and keeps you from having to look for a new unit.   

Fan On/Auto 

A typical AC unit has two fan settings: Auto and On. 

  • On: The fan is constantly running and the AC compressor is off unless the thermostat calls for cooling. The only time the fan stops is when you manually shut it off. 
  • Auto: The fan runs in intervals. In other words, the fan turns on automatically when the system is heating or cooling. When the thermostat reaches its programmed temperature, the system turns off both the heating or cooling and the fan.

Setting your fan to Auto is the most energy-efficient of the two options since the fan runs only when needed. An intermittent process also helps evaporate the moisture inside your AC unit faster than when the fan is set to On. How? When the AC fan is set to On, the moisture from the cooling coils does not have a chance to drain, but the opposite is true when the fan is set to Auto and the fan runs intermittently. The pauses in between each run cycle allows the moisture to drip outside. 

The only major downside to Auto is a lack of consistent air circulation.  

Fan model on ac

What Is the Purpose of Fan Mode in AC?

The purpose for your AC’s Fan Mode is to maintain constant room temperature without using too much energy. By shutting off the compressor, the feature saves your AC unit from too much wear and allows you to save money over time.

By circulating the inside air, the blower can also reduce unevenly warm or cold spots throughout your house.

Does Fan Mode on AC Bring In Outside Air?

In short, no. Fan Mode pulls in and recirculates only the air inside the house. This is the design for every type of AC unit.

Does Fan Mode on AC Save Electricity?

Yes, compared to a unit’s Cool Mode or Dry Mode, the Fan Mode feature saves you up to 85% of the energy used in Cool Mode. 

AC Fan Mode vs. Cool Mode

There are four major differences between your AC’s Fan Mode and Cool Mode:

  1. Fan Mode circulates the surrounding air, but it does not cool the air. Cool Mode, on the other hand, is designed to extract the hot air inside your home and drop the temperature is designed to extract heat from the air inside your home, dropping the air temperature.
  2. Fan Mode is not designed to reduce the humidity in a room. By comparison, Cool Mode is very effective at reducing humidity.
  3. Fan mode requires less wattage to run. On average, the fan requires 60 watts to 150 watts; however, Cool Mode runs on anything from 500 watts (a low wattage window unit) to 4,500 watts (a high wattage centralized unit).  
  4. Fan Mode turns the compressor off, whereas Cool Mode turns it on when the room is below the set point on the thermostat.

AC Fan Mode vs. a Normal Fan

In general, Fan Mode functions similarly to a normal ceiling fan or box fan, but there are some key differences to note: 

  1. Both Fan Mode and a normal fan circulate the surrounding air, but Fan Mode has low airflow (which is measured in cubic feet per minute, or CFM). This is especially the case when compared to a basic ceiling fan. The average ceiling fan moves approximately 4,000 CFM, while the average AC Fan Mode moves 400 CFM. 
  2. Fan Mode typically requires more energy than the average fan. Fan Mode requires 60 watts to 150 watts, whereas the average normal fan requires 40 to 75 watts. 

Written by

Rene has worked 10 years in the HVAC field and now is the Senior Comfort Specialist for PICKHVAC. He holds an HVAC associate degree and EPA & R-410A Certifications. Protection Status