Portable AC unit with vertical slats to seal space

Don't know what your new panel is made from, but I would look for a similar material from say the hardware store, or Tap plastics. One thing that might work would be those thin 1/8" thick translucent flexible cutting/rolling out boards from the Dollar Tree.

Cut a piece to fit the width, then the length to fasten up under the window frame plus enough allowance for overlap to glue to existing piece (1"- 1.5") I'm not to sure on what glue, E6000, or get the double-sided foam tape at the Dollar Tree in the hardware section.

I took the screen to glass store and had them cut me a piece of 1/4 inch plexiglass to fit the space. Tacked small pieces of wood in to hold the plexi. in place. works well - when not using it I just close the casement window and things are secure...not sure what came w/ your AC but bring the piece w/ you to glass co. and they'll figure something out for you.... good luck... SB

I don't have an answer. But I do have a question. What is the length and width of the window panel? I was thinking of getting one of these, but I don't know if it will fit in our vinyl windows with the security lock in place.

Kathy, what brand is your portable A/C? I have two different ones, also installed in left-to-right windows and both came with the same type of panel but it extends high enough to fill the window. Maybe the manufacturer sells replacement parts.

It's a DeLonghi, and when I went to their web site for parts they didn't have any so I found one on Amazon. Part of the fault is I live in an apt and the window doesn't close up on that panel properly, leaving spaces. Right now, with all the masking tape on it , it looks like "frankenstein" :)

onnie bee🐝For filling in spaces that need insulation,I went to Home Depot,and bought rolls of thick foam that's especially for insulating any thing, I too live in an apt, the foam can be used several times,i have two portable AC 's, any home hardware store will know what you want,if you can take a picture and show,then a rep of store will know your needs, one of mine ,is a challenge as exaust hose doesn't stay in place, need lots of duct tape, hope this helps B

Thank you so much for replying and the suggestion. I think your's might be set up different then mine. It's a DeLonghi and since my window opens sideways, it's a pain to set up. It came with 3 "slats" (and not enough pegs) which attach to each other. The problem with the unit is that, if it's cool outside, I have to take the unit out of the window. (it's like fighting with an octopus..you get the coil in, and then a panel will move..errrrrrrrrrrrrrrr

What if you had a piece of plexi cut to fit as an extension and then used silicone caulk to hold it all in place? That way you could use your original piece which already has the whole in it. It would be easy enough to cut the caulk off the sides when you remove the unit for the winter (easier than cleaning up behind duct tape).

I think I am going to try putting velcro straps on so if I want the window open I don't have to tear off masking tape..or I could just pray for cooler weather

sorry for the slow response..the width of the panel is about 4 inches

Try hot melt glue