The lift, which is being replaced as part of planned infrastructure improvement work, takes people to the escalators feeding Fort Regent.
The odd-floor lift will remain open throughout. Access to the Fort Regent escalator will still be available from levels 9 or 11 but islanders will need to use a single set of stairs to get to level 10.
Wheelchair users or parents with young children will still be able to access Fort Regent by parking in the dedicated spaces on levels 13, 14 and 15.
Every effort has been made to minimise disruption, including scheduling the project in the new year to avoid events at Fort Regent over the Christmas period.