Source file has:
header(\'Content-type: text/html; charset=iso8859-1\');
Source ajax (jQuery) script is:
$(document).ready
This is because you are displaying UTF-8 encoding of é (0xc3, 0xa9) as Latin-1. So the search_word was encoded as UTF-8 when it posted to PHP.
Try this,
$.ajaxSetup({ scriptCharset: "iso-8859-1", cache: false });