Jeep 2004 Grand Cherokee Owner's Manual page 172

172 UNDERSTANDING YOUR INSTRUMENT PANEL
The defroster will automatically turn off after about ten
minutes. For about five more minutes of operation, push
the button again. To prevent excessive battery drain, use
the defroster only when the engine is operating. The push
button also activates the heated exterior mirrors, if so
equipped.
CAUTION!
Use care when washing the inside of the rear win-
dow to prevent damage to heating elements. Use a
soft cloth and a mild washing solution, wiping
parallel to the heating elements. Also, keep all
objects a safe distance from the window to prevent
damaging the heating elements.