2008 Toyota Tundra Owners Manual - Page 430

07 11.20 XS19011a XS19012 4. Pull the filter out of the filter outlet. Inspect the filter on the surface. If it is dirty, it should be replaced. When installing the filter in the filter outlet, 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. 400 2008 TUNDRA from Apr. '08 Prod. (OM34477U)