By default, the temporary scanning folder for Scan Engine on Windows (32 bit) is C:\Program Files\Symantec\Scan Engine\Temp.
By default, the temporary scanning folder for Scan Engine on Windows (64 bit) is C:\Program Files (x86)\Symantec\Scan Engine\Temp.
By default, the temporary scanning folder for Scan Engine on Linux or Solaris is /opt/Symantec/Symantec Scan Engine/Temp.





References
 

For the Symantec AntiVirus Scan Engine 4.x version of this document, please see
Title: Add the temporary folder for Symantec Antivirus Scan Engine 4.x to exclusions for real-time scanner
URL: http://service1.symantec.com/support/ent-gate.nsf/docid/2003100716180054



Technical Information
If you updated from Symantec AntiVirus Scan Engine 4.x, your previous settings were migrated and may point to the /tmp folder on Solaris or the Windows Temp folder. Symantec recommends creating a Temp folder directly under the Scan Engine installation folder, pointing the Scan Engine settings to use this temp folder within the Scan Engine web interface, and excluding this location from realtime scanning by local filesystem antivirus.

NOTE:
Assuming that you also have a local antivirus scanner on other clients in the network, the following document is of interest to you:
'Symantec Scan Engine scan errors while trying to scan files across a network path or drives'
http://service1.symantec.com/support/ent-gate.nsf/docid/2008100811365154