I have a fairly wide horizontally sliding window. The AC units made for horizontal sliders are expensive. So, is there any problem with putting two normal window AC units side by side in the same window slot?

  • If you cannot install one regular A/C in your window I do not understand how you would install two? Typically there are two problems to solve: 1) A tall narrow window needs a tall narrow A/C. Not your problem. 2) Regular A/Cs have a flange on top that grabs the sash when lowered. You don't have that. So you can't install one, or two, A/Cs that way. I do not see what problem you have, that is solved by installing two A/Cs? What you probably need to do is hack together a frame that will attach securely to the top of your window and to the top of the A/C without needing a sliding sash.
    – jay613
    Jul 13, 2023 at 14:23

1 Answer 1


The only problem I see would be if the outside part of the units condensing coil and fan drew air from the side of the units and placing them side by side would restrict that air supply. If that were to happen, the units would not be able to remove the heat build up as part of the refrigeration cycle and the units would not cool. If the window is high enough you could stack the window units one above the other thereby not having any unit affecting the operation of the other. If the window is wide enough, Why not just buy 1 large unit to satisfy your cooling needs.

  • Good answer, I wonder if the op took your advice for a single unit, a single unit would be more efficient in this case.
    – Ed Beal
    Nov 29, 2018 at 14:44
  • Downvoting because if O/P needs help with his basic situation as described, it seems wrong to ask OP to hack together a way to install two A/Cs stacked on top of the other, safely. If that even exists.
    – jay613
    Jul 13, 2023 at 14:35
  • Well, @jay613, the OP seems to have enough basic gumption to try to hack two units side-by-side, so let's give him the benefit of the doubt... ;)
    – FreeMan
    Aug 12, 2023 at 13:16
  • @Freeman ok but let's stand a few feet away. :)
    – jay613
    Aug 12, 2023 at 17:40

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