Often, it just pulls off. Some older units will have the coils on the back. Now for a couple of projects you can do standing up. Inspect the glazing and caulking on the outside of your windows. Glazing compound is the putty that seals between the glass and the window frame.
Caulk is the putty that seals between the window frame and the house.
They are different. Replace any loose material with new. Since you will need to remove the window screen to get a better peep at the window's caulk, clean, inspect and make any necessary repairs to the screens. Fixing window screens alone could keep you busy until Memorial Day. If you need to replace any of the wire on screens facing east or west, consider using the type of screen that blocks more of the sunlight.