WooCommerce Correios - Free PAC when cart costs more than 100

functions.php

<?php
function custom_woocommerce_correios_shipping_methods( $rate ) {
    if ( isset( WC()->cart->subtotal ) && 100 <= WC()->cart->subtotal ) {
        $rate['cost'] = 0;
    }

    return $rate;
}

add_filter( 'woocommerce_correios_correios-pac_rate', 'custom_woocommerce_correios_shipping_methods' );