Default temp location is C:\Windows\Temp or %SystemRoot%\TEMP.
The location can be changed via GUI or PowerShell:
Set-ItemProperty -path "HKLM:System\CurrentControlSet\Control\Session Manager\Environment" -name TEMP "C:\TEMP" Set-ItemProperty -path "HKLM:System\CurrentControlSet\Control\Session Manager\Environment" -name TMP "C:\TEMP"