The Map Cleaner is used to automatically remove the game objects from the GTA San Andreas (PC) map, to make room for new maps. It will disable most map file entries in the gta.dat and delete all unneeded model (dff) and texture (txd) files from the game archives (img), taking care of shared objects.

For more information, help, and background info, visit this thread:
http://www.gtaforums.com/index.php?showtopic=198101