I'm having trouble with my wordpress ajax pulling the full page rather than the template part. The query isnt listening to the get_template_part() and is loading the whole page within it.

my category_loader in themename/inc/wp-ajax.

<?php
function category_loader() {

$cat_name = $_GET['category_name'];    
query_posts(array('category_name'=> "cat_name", "order" => 'DESC'));
$output = '';

while (have_posts()) : the_post();
get_template_part( 'content', "categoryloaders");
endwhile;

wp_reset_query();

die($output);
} // end my_custom_handler

add_action( 'wp_ajax_nopriv_category_loader', 'category_loader' );
add_action( 'wp_ajax_category_loader', 'category_loader' );
?>

my jquery script

$(function() {
    var ajaxurl = decodeURIComponent(ajaxurl);
    $(".cat-checkbox").change(function() {
        if(this.checked) {

            $('#primary').html("loading....")
            var the_cat = $(this).val();

            var data = {
                action: 'category_loader',
                category_name: the_cat
            };

            $.ajax({
                type: "GET",
                url: "ajaxurl",
                data: data,
                success: function(data){
                    $("#primary").html(data);
                }
            });
        }
        else {
            alert($(this).val() + ' is unchecked');
        }
    });

});

my output can be seen at this page, it's not of any sort of advertising but this is really confusing me right now. Any help would be great!