Gree XK86 Owner's Manual page 26

If there are multiple indoor units, press "IDU–" or "IDU+" to switch different indoor
units. Project numbers and error codes of indoor units will be displayed
correspondingly. If there are several errors in one indoor unit, error codes will be
displayed circularly at an interval of 3 seconds. If there is no error, "Null" will be
displayed.
After entering the interface of IDU project number view and locating, buzzer of
the selected indoor unit will ring until the wired controller exits the interface.
(2) View all IDU project No.
On the interface of project view, select "View All IDU Project No.". As shown
below, turn on or turn off "View All IDU Project No.".
Wired Controller (XK86 and XE76-33/H)
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