Hummer 2005 H2 - Manual (Page 119)

To adjust for compass variance, do the following:
1. Find your current location and variance zone
number on the zone map.
2. Press and hold the COMP button for five seconds
until a zone number appears in the display.
3. Press the COMP button on the bottom of the mirror
until the new zone number appears in the display.
After you stop pressing the button, the display
will show a compass direction within a few seconds.
Cleaning the Mirror
Use a paper towel or similar material dampened with
glass cleaner. Do not spray glass cleaner directly on the
mirror as that may cause the liquid cleaner to enter
the mirror.
Automatic Dimming Rearview Mirror
with Compass and Temperature
Display
The automatic dimming mirror dims to the proper level
to minimize glare from lights behind you after dark.
The mirror includes a compass reading and outside
temperature display in the upper right corner of
the mirror. The dual display can be turned on or off by
pressing either the TEMP or the COMP button.
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