Use a stud finder to locate two adjacent stud bays that will provide enough room for the opening.
Install a window air conditioner in the wall.
Extend the accordion panels from both sides of the air conditioner to the window sash track.
Secure the side panels with screws.
Once the window air conditioner is secure take some final steps to help keep the warm air outside and the cool air inside.
Your appliances should also have come with an installation guide that you can tape onto the wall and trace its outline.
Once you locate 3 4 wall studs mark them on the drywall with an x using a pencil.
Remove unit front cover and screws that hold the unit inside its case.
Install the case or sleeve into the opening.
Then measure the width of your through the wall air conditioner and transfer that measurement to the wall where the studs were marked.
Pull the unit forward while an assistant holds the case until it is fully withdrawn.
This allows for a replacement unit which might be larger.