Hummer 2007 H3 Owner's Manual page 127

To adjust for compass variance:
1. Find your current location and variance zone
number on the following zone map.
2. Press and hold the compass/temperature
button for six seconds until a zone number
appears in the display.
3. Press the compass/temperature 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 housing.
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