OnCollision2D Sprite Flip C#

I want to create a non-player controller sprite flip when they get from on collider to another so I can have a patrolling enemy, but I can't get the sprite to flip. Any suggestions?

using UnityEngine; using System.Collections;

public class JousterController : MonoBehaviour {

 public Vector3 pointB;
 Animator anim;
 public bool facingRight;
 
 // Use this for initialization
 IEnumerator Start () {
         var pointA = transform.position;
         while(true)
         {
             yield return StartCoroutine(MoveObject(transform, pointA, pointB, 3.0f));
             yield return StartCoroutine(MoveObject(transform, pointB, pointA, 3.0f));
         }    
 }
 
 IEnumerator MoveObject(Transform thisTransform, Vector3 startPos, Vector3 endPos, float time)
     {
         var i= 0.0f;
         var rate= 1.0f/time;
         while(i < 1.0f)
             {
                 i += Time.deltaTime * rate;
                 thisTransform.position = Vector3.Lerp(startPos, endPos, i);
                 yield return null;
             }
     }

 void CollisionEnter2D(Collision2D col)
 {
     if (col.gameObject.tag == "left")
     {
         facingRight = true;
         Flip();
     }
     
     if (col.gameObject.tag == "right")
     {
         facingRight = false;
         Flip();
     }
 }
 
     void Flip(){
      facingRight = !facingRight;
      Vector3 theScale=transform.localScale;
      theScale.x *= -1;
      transform.localScale = theScale;
      
  }

}