/diy/ - Do It Yourself

Posted a couple weeks back. Picrelated is a 2x4 frame to hold an A/C in a horizontal sliding window for an A/C designed for vertical hanging windows. Would like to ask about securing the middle horizontal piece properly. I'm using 3.5" deck screws for everything, but since that middle part would only have deck screws preventing the entire A/C from falling out of a high up window I would like to secure it better.

How can I do that? That is, how can I make sure that middle horizontal 2x4 in the frame is super duper secure and can take a ton of load pushing it out?

/diy/ I'm trying to make a frame for my window A/C unit because I have a horizontally sliding window but my A/C is for a vertical hanging window. The purple pieces of wood in the picture are 2x4s. The green box thing is the A/C. I would really appreciate some advice as I have no woodworking or /diy/ knowledge.

>What screws (what size, thread, etc I'm dumb a/f) do I use to put the 2x4s together? Did I use too many or not enough? Are the screws placed correctly?
>Is my design unsafe or are there any other glaring problems? I live on the 3rd floor with no balcony and its dangerous if the unit falls. I am worried that there is only a small lip at the bottom (0.5") and top rails keeping the A/C from falling out the window
>A slightly different design is to use a shorter 2x4 middle piece and have it sit between the vertical pieces like the top and bottom and move the entire A/C (and the 2x4 the A/C is resting on) forward slightly

Really I'm just super worried about it falling.