2007 Toyota Prius Owners Manual - Page 315

(c) Operating tips CAUTION Do not use the windshield air flow switch during cooled air operation in extremely humid weather. The difference between the temperature of the outside air and that of the windshield could cause the outer surface of the windshield to fog up blocking your vision. D On humid days, do not blow cold air on the windshield. The windshield could fog up because of the difference in air temperature on the inside and outside of the windshield. 27p126 D Keep the area under the front seats clear to allow air to circulate throughout the vehicle. D On cold days, set the fan speed to high for a minute to help clear the intake ducts of snow or moisture. This can reduce the amount of fogging on the windows. D The light sensor is located on the driver's side edge of the instrument panel. If you put anything on this area or cover the area, the sensor function may be adversely affected. D When driving on dusty roads, close all windows. If dust thrown up by the vehicle is still drawn into the vehicle after closing the windows, it is recommended that the air intake selector be set to OUTSIDE AIR and the fan speed selector to any setting except "OFF". D To cool off your Toyota after it has been parked in the hot sun, drive with the windows open for a few minutes. This vents the hot air, allowing the air conditioning to cool the interior more quickly. D If following another vehicle on a dusty road, or driving in windy and dusty conditions, it is recommended that the air intake selector be temporarily set to RECIRCULATE, which will close off the outside passage and prevent outside air and dust from entering the vehicle interior. D Make sure the air intake grilles in front of the windshield are not blocked (by leaves or snow, for example). 298