problem with jquery $.ajax and french characters when inserted in database

problem with jquery $.ajax and french characters when inserted in database

I get french characters who look like this é  but are é for example.
I am using jquery ajax and making a form validation with php then inserting in the database,
code:
  1.  $('#submit_maj_password_email').click(function(){
     var _data= $(this.form).serialize()
      $.ajax({
            type: 'POST',
             contentType: 'application/x-www-form-urlencoded;charset=iso-8859-1',
            url: 'validation_profil.php?var=maj_password_email',
            beforeSend: function(){},
            data:_data,
            cache: false,
            success: function(html){
             $('div#error').html(html)
          
                }
     
            }
         })
     
     })
















i have try many things but nothing seems to get rid of the problem and i know it's because of jquery ajax because if i make a simple insert in database using only PHP eveything works fine.

regards