Change System Mode on CCU Matthew Mulheran July 05, 2019 14:31 Updated 1. Select 'System' in the upper-left. 2. Select either 'Off', 'Auto', 'Cool Only', or 'Heat Only'. Related articles Passwords on CCU Installer Options Change Desired Temperature on CCU Changing Schedule on the CCU Comments 0 comments Please sign in to leave a comment.