2004 Toyota Prius Owners Manual - Page 197

(b) Windshield defogging and defrosting If manual on−off of the air conditioning is desired- Touch the "A/C" switch to turn the air conditioning on and touch it again to turn the air conditioning off. If the system is used for ventilation, heating in dry weather or removing frost or exterior fog on the windshield, turn the air conditioning off once it is no longer required. This will improve fuel economy. The air conditioning can be used for year− round automatic temperature control including cooling and dehumidifying operation. When the front windshield switch is touched, the air conditioning is set to operate and the OUTSIDE AIR mode is set. If you touch the front windshield switch once again while in the FRONT WINDSHIELD mode, the mode then returns to the last mode used. The indicator will come on in the instrument cluster while the FRONT WINDSHIELD mode is on. 27p116a CAUTION To remove interior fog on the windshield- Touch the front windshield switch. To remove frost or exterior fog on the windshield- 1. Touch the upper side of the temperature control switch until maximum figure appears on the temperature display. 2. Touch the front windshield switch. 3. Push the "HI" of the air flow control switch to obtain a maximum air flow. 4. Leave the air conditioning on−off button off. Do not use the front windshield 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. 185