2004 Toyota Highlander Owners Manual - Page 256

'04 HIGHLANDER_U (L/O 0308) 5. Remove case. the filter from the filter 6. Inspect the filter on the surface. If it is dirty, it should be replaced. When installing the filter and filter case, keep the arrow pointing up. INFORMATION The air filter should be installed properly in position. The use of air conditioning with the air filter removed may cause deteriorated dustproof performance and then affect air conditioning performance. 256 2004 HIGHLANDER from Aug. '03 Prod. (OM48478U)