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 decreases when the vacuum hose of the air control valve is pinched.
  
  Fig 1: Pinching Air Control Valve Vacuum Hose
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
4. Check that the engine rotations increases when the hose is released.