Loading texture from Resources folder not working C#

Question

So I want to load different textures for my game object when different conditions are met. There are no errors when I compile this code. The colours change according to the condition, that part does work. The textures do not load though. The textures are stores in a Resources folder in Unity. The first code works but the second does not. Why is this the case? Below is my code:

    using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Level4 : MonoBehaviour
{

    Material _mat;
    GameObject Sphere;


    // Use this for initialization
    void Start()
    {
        Sphere = GameObject.FindWithTag("Player");
        //Material _mat = GameObject.FindWithTag("Player").GetComponent<Renderer>().material;

    }

    // Update is called once per frame
    void Update()
    {
        try
        {


            if (Input.GetKeyDown(KeyCode.UpArrow))
            {
                Renderer _rend = GetComponent<Renderer>();
                Material _mat = _rend.material;
                _rend.material.mainTexture = Resources.Load("face1") as Texture;
                _mat.color = Color.red;
            }
        }
        catch (System.Exception)
        {
        }
    }
}

this is the second code that does not work:

    using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.IO.Ports;
public class arduino : MonoBehaviour
{

    SerialPort sp = new SerialPort("//.////COM6", 9600);// Com port and the baud rate of the arduino
    Material m_Material;
    GameObject Sphere;



    void Awake()
    {
        Sphere = GameObject.FindWithTag("Player");
        m_Material = GameObject.FindWithTag("Player").GetComponent<Renderer>().material;
    }
    void Start()
    {
        if (!sp.IsOpen)
        { // If the erial port is not open 
            sp.Open(); // Open 
        }
        sp.ReadTimeout = 250; // Timeout for reading 
    }

    // Update is called once per frame
    void Update()
    {
        if (sp.IsOpen)
        { // Check to see if the serial port is open 
            try
            {

                string portreading = sp.ReadLine(); // get the string output of the serial port 
                float amount = int.Parse(portreading);



               if ((amount > 251f))
                {

                    Renderer _rend = GetComponent<Renderer>();
                    m_Material = _rend.material;
                    _rend.material.mainTexture = Resources.Load("face1") as Texture;
                    m_Material.color = Color.red;

                }
            }
            catch (System.Exception)
            {

            }

        }

    }
}

Answer 1

Take a look at the documentation for examples. Renderer.material

also make sure you have placed the texture in a folder named Resources.

you can reference the Renderer then get a reference to the material and then load it and change the color.

if ((amount > 151f) && (amount < 200f)) 
{
    Renderer _rend = GetComponent<Renderer>();
    Material _mat = _rend.material;

    //make sure face2 is in Assets/Resources 
    _rend.material.mainTexture = Resources.Load("face2") as Texture;
    _mat.color = Color.blue;
}