Then you need to find them directly and clean them manually.
This can happen because the program crashed or the developer of the program simply forgot to add the code needed to delete the temporary files after the program is done with them. Some programs create temporary files and then leave them behind - they do not delete them. If you did an Archive and Install, than you will have a Previous Systems folder. Also, you may have deleted an unneeded user from your system, but unless you clicked Delete Immediately you will have compressed deleted user accounts in your Users folder. Empty iPhoto's, iMovie's and Mail's built in Trash too. The Trash icon in your Dock is not the only trash you need to empty. Here are some things you can do to free up disk space. Some simple hard-drive cleaning measures can reclaim lost disk space and get rid of applications and data files that you no longer use or want. However, no matter how big your drive, you'll be amazed at how quickly application installs, browser caches, and temporary files can eat up your free space and clutter your system.
Nowadays, hard drives feature amounts of space.
Mac OS X Lion version 10.7 is the eighth and current major release of Mac OS X, Apple's desktop and server operating system for Macintosh computers. How to free up hdd space on Mac OS X 10.7 Lion?