I have an air conditioning unit hooked into a door on full blast, but it is still hot in the room I am in. I also have a floor fan (~3 ft diameter). I am wondering if it is better to have the fan on (back against the wall) blowing the cold air coming from the AC farther into the room, sitting inside another doorway (blowing the hot air out of the room) or turned off.

Fan blowing ac across room

Fan blowing ac across room
Fan blowing air out door

Fan blowing air out door

  • is the A/C unit completely within the room? You have to have the hot side outside the room for it to work. Commented Jul 26, 2016 at 15:47
  • Yes, the AC has two exhaust tubes that are pointed out the door.
    – Austin
    Commented Jul 26, 2016 at 16:08

2 Answers 2


REVIEW: It is important to isolate the air conditioner air flow. Air conditioners work by producing heat as part of the "cooling" process. Hot air is pushed out of one side and cool air from the other. Keep the hot part out of your area as much as possible. Often, the hot air tubes become radiant heaters, themselves. Keep them as short as possible and insulate them if possible.

The doors into the room appear to be close together. If the doors open into a hallway or into a common room, that area will become a larger room to cool, in effect.

If the adjacent room is cooler than yours, the fan alone in the doorway will equalize the temperature by recirculating and mixing the air with both doors open. If not close the door to reduce the load on your air conditioner.

The Fan: Once you have isolated yourself in your environment, position the fan to create optimal air circulation within the room by having all the air moving in the same direction. Try putting it against the centre of a wall so that air is pushed around the room in as smooth a circular pattern as possible.


The fan is irrelevant to the actual cooling, all it will do is redistribute air.
Put it where it will blow across you - you will perceive the air-flow as cooling, because of the evaporative effect & also it will move the small layer of body-heated air away from you.

The most important thing is to seal the room as best you can.
Close the second door completely.
Insulate the hot air output & the door it goes through with towels or bedding, to make a barrier between the temperature differential of outside the room & inside.

Two things you cannot do with air-con...
1) cool the entire world - any gap open to the outside will negate the cooling effect & the drying effect. If the air-con struggles to get the temperature down as far as you'd like it, the humidity-reduction effect alone would be better than the outdoors.
2) cool any space that includes both the input & output - the net effect would be to heat the space. You must isolate the heated output completely from the cooled area.

  • I lived in apartment I tried to keep warm in winter and cold in summer. I lived there 6 years. It had a wall heater/air conditioner like this. I froze in the winter and roasted in the summer for the first 4 years. Then I got smart and got a small floor fan and pointed it at about 45 degrees toward the ceiling in way that looked like if it was a beam of light would hit the ceiling, bounce to the wall, then bounce to the floor. The last two years in that apartment were warm in the winter and cool in the summer.
    – gman
    Commented Dec 10, 2018 at 15:05
  • It was clear the air was not circulating well enough by the air conditioner alone so in the summer the floor would be cool but hot near the ceiling. In the winter freezing near the floor, hot near the ceiling. It was clear the air needed circulation to actually make all the air comfortable instead of some tiny layer in the middle. Adding the fan moved the cold air up in the summer or the hot air down in the winter and ended up helping the air conditioner keep the entire place a comfortable temperature.
    – gman
    Commented Dec 10, 2018 at 15:08

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