how to install a window A/C unit on a sideways sliding window
 

I need to install a window A/C unit on a sideways sliding window. The window must be open to do this. The A/C unit sits at the bottom, leaving the entire top part of the window open (and unable to be shut due to A/C unit). Any ideas on how to seal off the top part? I was thinking of trying to get sort of clip to hold a piece of custom cut plexiglass to fit in that hole. Any other ideas on how to handle this problem? Please also send your response to nama878 at gmail (dotcom)

Welcome to the Forum Nama:
Have the plexiglass cut a little full and you can probably snap it into the tracks you have there, and in behind the open part of thewindow. Some silicone caulk on top of the A/C should finish it off.
Glenn