camera script problems

hey guys this script works it switches my camera`s when i push c but how can i tweak it that it will automaticaly switch after 10 seconds to camera2

thankyou

var camera1 : Camera;
var camera2 : Camera;
private var cameraSwitch : boolean = true;

function  Update ()
{
if (Input.GetKeyDown ("c"))
{
cameraSwitch = !cameraSwitch;
camera1.enabled = cameraSwitch;
camera2.enabled = !cameraSwitch;
}
}

var camera1 : Camera;
var camera2 : Camera;
var oldTime = 0;
private var cameraSwitch : boolean = true;

function  Update ()
{
    if (Input.GetKeyDown ("c") || Time.time > oldTime)
    {
    oldTime = Time.time + 10;
        cameraSwitch = !cameraSwitch;
        camera1.enabled = cameraSwitch;
        camera2.enabled = !cameraSwitch;
    }
}

Have fun!

  function Start () 
     {
 camera1.enabled = true;
 camera2.enabled = false;
 camera3.enabled = false;
 delay1(); //user defined function
    }

 function delay1()        
    {
  yield WaitForSeconds (10);
  camera1.enabled = false;
  camera2.enabled = true;
    }

do not use in yield statement in update function