Does fan mode on window AC bring in outside air?
No, air conditioners do not bring in fresh air from the outside. That's not how they were designed. What actually happens is that your air conditioner uses a fan to draw air into the unit and disperse it through a structure. This results in recycled air.
No, 'Fan Mode' does not bring in fresh outside air. That is not how air conditioners are designed. When you switch to 'Fan Mode,' the fan will take in air from inside your room into the unit itself, then blow it back into the room. The air is being recycled by the air conditioner's fan.
Fan mode on an AC unit means that the fan will run without the compressor turning on. This can be a good option if you want to circulate the air in your home without cooling it. It can also be helpful if your AC unit is not blowing cold air but the fan is still working.
Air Conditioner Fan Mode Setting
The fan of an AC unit connects to your indoor air handler. The fan will return the warm air in your home to the condenser. The re-circulated air will come back to the air handler where it's converted to cool air and dispersed throughout your system of ducts and vents into your home.
Air conditioners are never designed to bring in air from outside the home. They are considered a sealed system in that they will only operate on the air within the building's ecosystem in which they are installed.
The fan only turns on when cooling or heating is required. If you are generally as comfortable in one room of your home as the next, you'll want to use the AUTO setting. The AC fan kicks in when needed and stops running when the job is done.
Using a fan with your A/C can significantly reduce the hot temps in your home – and reduce your energy bill. By positioning fans near window unit A/Cs or near central air vents, you can circulate the cool air over a wider area.
Fan Mode. When the fan mode is activated, the internal fan within the AC circulates air within a room. This is carried out without any cooling, much like a normal fan. The major advantage of using the fan mode in ACs is the obvious energy saving due to the absence of the compressor function.
How to keep your house cool in the summer without AC - YouTube
But do window AC units use a lot of electricity? Well, compared to central units, they do not. A window AC unit uses less than ⅓ of the amount of energy it would take to run a central unit for the same amount of time. But if you have more than one unit, it can quickly add up.
Does the fan mode on air conditioner use less electricity?
Operating the air conditioner in fan mode uses significantly less energy than other AC modes, including cooling, heating and dry mode. This is because it takes less power to run the fan than the compressor.
Because the fan blows constantly, most of the moistures evaporates and gets blown right back into your house! So, quick recap: The AUTO setting lets your AC properly dehumidify your home by stripping the air of moisture and pushing that moisture outdoors.

- Run the Fan When You're Not Home. You don't want to waste energy when you're out of the house. ...
- Filter the Air During Allergy Season. Any time you notice a runny nose, a dry throat or a persistent cough, it could point to your allergies. ...
- Share the Love.
In short, no. Though in split system air conditioning design, commonly heat pumps, part of your system is located outside your home, it does not take in outside air. Outside air is brought into the system from an intake which is generally located by your furnace, but is occasionally its own, separate system.
Standard compression-cycle air conditioners (both window units and whole-house models) remove moisture through condensation, as described above.
It works extremely well to filter out particulates such as ash, soot, and other debris from nearby fires, and to neutralize the harmful gasses, chemicals, and odors that make up smoke.
If you have a portable air conditioner with a single hose, typically vented out of a window, do not use it in smoky conditions because it can result in more smoke being brought inside. Consider other cooling options like a fan or window air conditioner.