Air Conditioner Vs. Running the AC Fan

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Window-box units can cool or fan the air.

It's easy to understand what an air conditioner is supposed to do, but sometimes knowing what each function does can get complicated. The fan mode and switches are one such example. It may seem logical to think that a fan for an air conditioner is the same as a fan that you use in a room, thought this is not the case. The fan mode for central air conditioning systems is entirely different from the fan mode for window-box air conditioning units.

Air Conditioner

An air conditioner disburses cool air into rooms to make them more comfortable on hot summer days. A central air conditioning system circulates cool air throughout the entire home. There are also window air conditioners that are used to cool a single room. Central air works with your home's overall HVAC (heating, ventilation, air conditioning system), while room air conditioners work as stand-alone appliances.

Air Conditioner Fan Mode

The fan for central air conditioning systems is connected to your furnace. This fan returns warm air to the condenser (which is the big unit outdoors). The air is re-circulated from the condenser back to the furnace, where it is turned into cool air and disbursed through ducts and vents into the rooms. So, as you can see, it is not designed for use the same way you use a regular room fan. Window-box air conditions are, however, an exception. The fan mode does indeed work like a traditional room fan. If you switch the dial to "fan", it will circulate the air the room. However, it will not blow cool air. To get cool air you have to switch the dial to the "air conditioning" mode.

Energy Efficiencies

Your air conditioner may account for as much as 50 percent of your energy use during the summer months. To get the most out of your home air conditioning unit, be sure to review your owner's manual and follow usage recommendations from the manufacturer. Look for an Energy Star-rated unit if you are in the market for a new air conditioner, and a unit that has a SEER rating of at least 14. That will assure you that the unit meets minimum requirements for efficient operation. If you don't have a programmable thermostat, do your wallet a favor and invest in one. Use the "set it and forget it" principal and keep it at 78 degrees F to keep your energy use (and your bills) low.

Usage Cautions

It is important to remember that you should never use the "fan" mode for a central air conditioning unit the same way you use a regular room fan. This can cause problems with your thermostat and overall HVAC system. Running the fan for a long period of time with any system (central air or window box) will also increase the humidity in the room. This can further confuse your thermostat if you have central air conditioning. According to the California Energy Commission, it is more efficient to keep your air conditioning system fan set to "automatic" rather than to run it continuously.

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Cheryl Munson

Cheryl Munson has been writing since 1990, with experience as a writer and creative director in the advertising industry. She holds a Bachelor of Arts in journalism with a focus on advertising from the University of Wisconsin in Madison.