I can't find any info on this question, and this might be a stupid idea... but anyway:
The temperature in the attic is ca. 130F, 3pm, outside temperature 90F. ( Florida, 17y/o house ) Can I direct/force part of the air coming out of the outside A/C compressor via the soffit into the attic to cool it down? The air coming out of the compressor is way colder than the attic temperature. I am thinking about some prove of concept temporary installation to compare the results without doing too many changes, and without regretting that I tried.
But before I even attempt this I want to ask you guys.
Many thanks!

  • 3
    the outside unit of an AC system generates heat because the AC moves heat from the inside of the house to the outside unit ... just install a separate fan for the attic
    – jsotola
    Commented Aug 22, 2020 at 19:43
  • Are you talking about running a duct into the attic, or are you somehow expecting to find cold air wandering off of the outside unit, capturing that and directing it up there? As @jsotola said, the air coming out of the outside unit is going to be hot because that's where it dumps the heat from inside the house.
    – FreeMan
    Commented Aug 22, 2020 at 19:56
  • thanks! running sort of a duct through the soffit. I am aware that the compressor's air pushed by the fan is 'hot' - it is still way colder than the temperature in the attic
    – MikeF
    Commented Aug 22, 2020 at 21:06
  • Is that opinion supported by any kind of measurement? Or is it subjective? Commented Aug 22, 2020 at 21:31
  • 1
    Outside is 90 and the attic is 130. Most of the condensers I sercive, throws 120-150 degree air out of the unit. You would be better off installing an attic fan.
    – Gunner
    Commented Aug 22, 2020 at 22:42

1 Answer 1


Directing air from outside compressor into your attic would reduce the air flow from your compressor and probably decrease the cooling ability of it. A better solution would be to install an attic fan that vented to the outside. The problem with that is that you suck in humid air from the outside. If you've got good insulation on the attic floor why is the attic temp a problem? I live in S. Florida and my attic temp is really hot but with great insulation it doesn't affect the living space below.

  • thanks! This was my concern: lowering the efficiency of the compressor - this is also why I said 'part' of the air. The fan pushes a lot of air, so even directing a percentage through it would create higher air circulation than what it is now. There is places already where the outside air flows in ( humid ) & out the attic: soffit and ridge. There is no other vent types. A very good point here is the insulation - it is the standard (y2003) 7in wool type. A great deal made me buy an IR Flir camera 10y ago, and the ceiling temperature in many spots shows ~90F which definitely could be improved
    – MikeF
    Commented Aug 22, 2020 at 21:20
  • efficiency: you have to give to gain... if the gains are too little, it is not worth whatsoever - it can only cause other issues such as rising humidity, and structural, especially during the high winds... I kept thinking about it and without any measurements, and stats, it is difficult to tell if this would make any sense. I think I have to think how to improve the insulation, and get better vents when it comes to replacement of the roof ( it will be due soon anyway ). In any case, thank you for your comments/answers. Mike
    – MikeF
    Commented Aug 22, 2020 at 21:30
  • Really hot might not be a terrible thing. No mold will grow at 130F. No critters will move in. As noted with insulation the heat will not come down to get you. Leave it hot.
    – Willk
    Commented Aug 22, 2020 at 22:50

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