2009 Toyota Highlander Owners Manual - Page 296

3-1. Using the air conditioning system and defogger CAUTION n To prevent the windshield from fogging up Do not use during cool air operation in extremely humid weather. The difference between the temperature of the outside air and that of the windshield can cause the outer surface of the windshield to fog up, blocking your vision. NOTICE n To prevent 12-volt battery from being discharged Do not leave the air conditioning system on longer than necessary when the hybrid system is off. 268