You can do this by opening the File Explorer (press Ctrl E), then proceed by clicking on the “This PC” in the left window pane, and typing in the keyword “acad.pat” into the top box in upper right and press Enter. The first step in locating your AutoCAD hatch pattern (.pat) file is to search for it within Windows. Here’s a quick tip on how to locate your AutoCAD Hatch Patterns and then set the path. The problem may arise when you have multiple installations of AutoCAD you may have more than one.
The path to your hatch pattern definitions can be found in the Support folder in AutoCAD.
This PAT file is loaded every time you open a drawing in AutoCAD, and is used to set the default hatch patterns available in AutoCAD. The acad.pat (pattern / hatch) is a text file in AutoCAD that contains the source code for your hatch patterns.