How to stop head from going through stuff?

So I have a crouch script but for some reason whenever I go under something and then stand up my head goes through the object I am supposed to be standing under. Any help here would be amazing, also I am not using a rigidbody controller so anything that deals with that is probably out of the question. Thanks in advance, please help!

 var crouchSpeed : float = 3;
 var charController : CharacterController;
 var Player : Transform;
      
     private  var charHeight : float;
     private  var pos : Vector3;
 
 
 
     function Start (){
         Player = transform;
         charController = GetComponent(CharacterController);
         charHeight = charController.height;
 
     }
 
 
 
     function Update (){
          var h : float= charHeight;
          
         if (Input.GetKey(KeyCode.C))
         {
             h = 1;//charHeight*.05f;    
         }
 
          var lastHeight : float= charController.height;
         charController.height = Mathf.Lerp(charController.height, h, Time.deltaTime * 5);
         pos.x = Player.position.x;
         pos.z = Player.position.z;
         pos.y = Player.position.y + (charController.height - lastHeight) / 2;
         Player.position = pos;
 
     }