Installing A/C unit inside of a horizontally sliding window.

Picture of Installing A/C unit inside of a horizontally sliding window.
Most inexpensive A/C units are designed for vertical sliding windows, which creates a problem if you have horizontal sliding windows. Installing an A/C unit inside of a horizontally sliding window does not have to look bad, and it does not require any special brace.

I can't take responsibility for your installation, theft, break ins, and your A/C falling out of your window.
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Step 1: Materials required:

Picture of Materials required:
The unit I am working with is a Haier 8000 BTU from Walmart. Yours might be different but the idea is the same.

1/4" Rubber Foam Weatherstrip
Window screen frame
Plexiglass - Home Depot
Screws, self drilling, 1/4"
C-channel Aluminum pieces 3/8' and 1/2' sold in 8' length
Silicone - Home Depot
Nut Rod Coupling  and a screw that fits.
jcharles118 months ago
Thank you so much for this! You are a life saver!!

Any suggestions for a removable caulk?

I have been doing this for years, and honestly, there is NO such thing as removable caulk ;) There IS such thing as a chemical caulk remover and it is the most amazing stuff ever. We have used it ever year on vinyl windows to remove our a/c units and we haven't had any problems at all! Awesome ;)

I have a question about the rod nut coupling... I'm presuming you need a very strong power drill to drill a hole through its side as explained in one of the steps. Do they offer predrilled versions at hardware stores? Also, that part where you slide down the vertical C channel and drill another hole where it will meet the coupling that was screwed into the horizontal channel, do you screw beside it, above it, underneath it, make another hole through the coupling? I got a little confused by that step. Lastly, are these instructions to build a frame into the existing window frame with or without the plastic frame that comes with these units?
ikssk (author)  alex.melodymaker1 month ago
Rod coupling can be drilled with any metal drill bit. No they do not offer pre drilled versions at the store. I used the frame that came with the unit, but your window might require something else.
Ok cool, thanks for the quick response.
vinayvinay16 months ago

Hey.. nice post.. I just moved to USA from India. So, I have no idea where to get these material to fix the AC. (back in India the AC companies install it at home free of cost)..

Can you please give me some online/offline links where I can buy these stuff.?

ikssk (author)  cinderellato2 years ago
Good luck
ikahoshi3 years ago
Thank you for posting this. I think this might be just the thing for my situation.
sierrabravo5 years ago
i have seen a few units like this before.  if you are worried about theft or break-ins, I would suggest putting one or a few pre-cut pieces of wood or metal on between the moving window and the left frame to secure that sliding window in the position it's in so it cannot move left or right.
ikssk (author)  sierrabravo5 years ago
That is a good idea, I did not have to worry about that since the window is on the second story.
rjlewis745 years ago
Great instructable. I have been looking to put something like this together for sometime. Thanks
ikssk (author)  rjlewis745 years ago
Thank you