2010 Toyota Avalon Owners Manual - Page 231

3 -1 . U sing t he a ir c ondit ioning syst e m a nd de fogge r Rear w indow and outside rear view mirror defoggers These features are used to defog the rear window, and to remove raindrops, dew and frost from the outside rear view mirrors. With outside rear view mirror defoggers Without outside rear view mirror defoggers Press the button to turn on the rear window (and outside rear view mirror) defoggers. The defoggers will automatically turn off after approximately 15 minutes. Pressing the button again also turns the defoggers off. The operation time changes according to the ambient temperature and vehicle speed.