Air Control Valve Inspection

Turn air conditioning switch off .
Check idle-up :
1. Start the engine and run it at idle.
2. Fully turn the steering wheel.
3. Check that the engine rotations decrease when the vacuum hose of the air control valve is pinched.
  
  Fig 1: Locating Vacuum Hose (4.7L)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
4. Check that the engine rotations increase when the hose is released.