NISSAN 2012 Sentra - Manual (Page 151)

Heated mirrors (Canada only) (if so
equipped)
Some outside mirrors can be heated to defrost,
defog, or de-ice for improved visibility. Push the
rear window defroster switch to activate the heat-
ing function. Push the switch again to deactivate,
or the heating function will automatically turn off
after approximately 15 minutes.
3-30 Pre-driving checks and adjustments