Jeep 2011 Grand Cherokee - Owner Manual - Manual (Page 336)

NOTE: In cold weather, use of Recirculation mode may
lead to excessive window fogging. The Recirculation
mode is not allowed in the Floor/Defrost Mix and
Defrost modes to improve window clearing operation.
Recirculation will be disabled automatically if these
modes are selected.
Operating Tips
Window Fogging
Windows will fog on the inside when the humidity inside
the vehicle is high. This often occurs in mild or cool
temperatures when it’s rainy or humid. In most cases,
turning the air conditioning (pressing the A/C button) on
will clear the fog. Adjust the temperature control, air
direction, and blower speed to maintain comfort.
As the temperature gets colder, it may be necessary to
direct air onto the windshield. Adjust the temperature
control and blower speed to maintain comfort. Higher
blower speeds will reduce fogging. Interior fogging on
the windshield can be quickly removed by selecting the
DEFROST mode.
Regular cleaning of the inside of the windows with a
non-filming cleaning solution (vinegar and water works
very well) will help prevent contaminates (cigarette
smoke, perfumes, etc.) from sticking to the windows.
Contaminates increase the rate of window fogging.
334 UNDERSTANDING YOUR INSTRUMENT PANEL