Jquery function does not access variables from form

I need to calculate the value of a service of a pethop project, where it is necessary to inform the data: id_porte (small, medium, large), id_categoria_animal (dog, cat) tosa or bath with tosa), since the values vary according to the size of the animal, category and the requested service.

However, the id_categoria_animal and id_porte information is already filled in the form when the customer's CPF is entered on the previous page, so when the service is selected in a select field, the value automatically loads but is not giving right and did not find the error, I'm using the codeigniter framework.

This is the controller:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

Class Consulta_cpf extends CI_Controller{
    function __construct(){
        parent::__construct();
        $this->load->helper('form');
        $this->load->library('form_validation');
        $this->load->model('cliente/dados_cliente', 'dados');   
        $this->load->helper('date');    
    }

    public function index(){
        $this->form_validation->set_rules('cpf', 'CPF', 'required|trim|exact_length[11]|numeric');

        //VERIFICA SE AS REGRAS COM O CPF DIGITADO FORAM EXECUTADAS.
        if($this->form_validation->run() == FALSE){
            if(validation_errors()){
                die('<p> <a href="'.base_url('agendar_servico').'"> Clique aqui  </a> para voltar </p>'.validation_errors());
            }
        }

        if(isset($_POST['acao']) && $_POST['acao'] == 'Pesquisar >>'){
            $cpf = $this->input->post('cpf');

            //VERIFICA SE O CPF DO CLIENTE EXISTE NO BANCO DE DADOS.
            try {
                $pessoa = $this->dados->select_nome_pessoa($cpf);
            } catch (Exception $e) {
                die('<p> <a href="'.base_url('agendar_servico').'"> Clique aqui </a> para voltar</p>'.$e->getMessage());
            }

            $id_pessoa = $pessoa['id_pessoa'];
            $id_cliente = $this->dados->select_id_cliente($id_pessoa);
            $animal = $this->dados->select_animal($id_cliente);

            $dados['nome_cliente'] = $pessoa['nome_pessoa'];
            $dados['id_cliente'] = $this->dados->select_id_cliente($id_pessoa);
            $dados['id_animal'] = $animal['id_animal'];
            $dados['nome_animal'] = $animal['nome_animal'];
            $dados['id_cat_animal'] = $animal['id_cat_animal'];
            $dados['nome_cat_animal'] = $animal['nome_cat_animal'];
            $dados['id_porte'] = $animal['id_porte'];
            $dados['nome_porte'] = $animal['nome_porte'];
            $dados['idade'] = $this->dados->select_idade($animal['data_nasc_animal']);
            $dados['data'] = $this->dados->select_data();
            $dados['servicos'] = $this->dados->select_servicos();
            $dados['consulta_func'] = $this->dados->consulta_func(1);
            $dados['cpf'] = $this->input->post('cpf');

            $this->load->view('cliente/agendar_servico', $dados);
        }
    }

}

This is the model (only the function that matters in this case is the value query)

public function consulta_valor($id_servico, $id_cat_animal, $id_porte){
    $options = "<option> Valores </option>";

    $this->db->select('*');
    $this->db->from('valores');
    $this->db->where(array('id_servico' => $id_servico, 'id_cat_animal' => $id_cat_animal, 'id_porte' => $id_porte));
    $query = $this->db->get();

    if($query->num_rows() > 0){
        foreach($query->result() as $linha){
            $options .= "<option value='{$linha->id_valor}'> $linha->valor </option>";
        }
        return $options;
    }else{
        return false;
    }
}

This is the function for the jquery run, which is inside the controller / ajax

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

Class Valor extends CI_controller{
    function __construct(){
        parent::__construct();
        $this->load->model('cliente/dados_cliente', 'dados_cliente');

    }

    public function get_valor(){
        $id_servico = $this->input->post('id_servico'); 
        $id_cat_animal = $this->input->post('id_cat_animal');
        $id_porte = $this->input->post('id_porte');         
        sleep(1);
        echo $this->dados_cliente->ff($id_servico, $id_cat_animal, $id_porte);
    }
}

This is the header function with jquery.

$(function(){
        $('#servico').change(function(){

            $('#valor').attr('disabled', 'disabled');
            $('#valor').html("<option> Carregando... </option>");

            var id_servico = $('#servico').val();

            $.post(base_url+'index.php/ajax/valor/get_valor',{
                id_servico : id_servico
            }, function(data){
                $('#valor').html(data);
                $('#valor').removeAttr('disabled');
            });
        });
    });

And finally this is the view (well, just a part of it):

echo form_label('Serviços: ');
echo "<select id='servico' name='servico'>";    
echo $servicos;
echo "</select>";

echo form_label('Valor: ', 'valor');
echo "<select id='valor' name='valor' disabled=''>";
echo "<option>valor</option>";
echo "</select>";