Service1.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Net;
using System.ServiceProcess;
using System.Text;
using System.Threading;
using System.Threading.Tasks;


namespace WindowsService
{
   public partial class Service1 : ServiceBase
   {
	private static Thread thServico = new Thread(Servico);

	public Service1()
	{
	   InitializeComponent();
	}

	private static void Servico()
	{
	  for(;;)
	  {
	       GravarTextoEmArquivo("SERVIÇO SENDO EXECUTADO AS " + DateTime.Now.ToString() + ".");
	       // Coloca a Thread para dormir por uma hora
	       Thread.Sleep(3600000); //1 hora   
	  }
	}
       
	protected override void OnStart(string[] args)
	{
	   try
	     {  
		AbrirArquivo("SERVIÇO INICIALIZADO AS " + DateTime.Now.ToString() + ".");
		thServico.Start();
	     }
	     catch(Exception e)
	     {
		Console.WriteLine(e.Message);
	     }
	}

	protected override void OnStop()
	{
	     try
	     {
		AbrirArquivo("SERVIÇO PARALISADO AS " + DateTime.Now.ToString() + ".");
		thServico.Abort();
	     }
	     catch(Exception e)
	     {
		Console.WriteLine(e.Message);
	     }
	}
    
	public static void GravarTextoEmArquivo(string texto)
	{      
		StreamWriter vWriter = new StreamWriter(@"C:\Log\LogServico.log", true);
		vWriter.WriteLine(texto);

		vWriter.Flush();
		vWriter.Close();
	}    
    }
}