WARNING: This page is about a different car, the 2002 Volvo C70, 2001 Volvo C70, 2000 Volvo C70, 1999 Volvo C70, and 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Hose To Firewall
Courtesy of VOLVO CARS OF NORTH AMERICA.
Squeeze the hose shut (1) and disconnect the hose from the firewall.
Remove:
the locking from the hose and reinstall on the firewall.