Magento – Restrict shipping methods to certain products

I used the following code in my ../template/checkout/onepage/shipping_method/available.phtml custom theme template inside the foreach shippingrategroups loop....

USPS and additional shipping methods must be enabled. It forces any APO address to USPS if it finds a city or region code that matches.

         <?php //Added to force USPS for APO
            $address = $this->getAddress();
            $apoStateCodes = array("AE", "AE", "AP");
            $apoCityCodes = array("APO", "FPO", "DPO");

            $regionCode = Mage::getModel('directory/region')->load($address->getRegionId())->getCode();

            $carrierName = strtoupper(str_replace(" ", "", $this->getCarrierName($code)));
            if (in_array($regionCode, $apoStateCodes) || in_array($address->getCity(), $apoCityCodes))
            {
                // IT IS APO, so skip iteration of non-USPS
                if ($carrierName != "USPS")
                {
                    continue;
                }
            }
            else
            {
                // ITS A NORMAL ADDRESS
                if ($carrierName == "USPS")
                {
                    continue;
                }
            }

            /* OLD WAY OF DOING THINGS (only works on PO box)
            if (preg_match("/p\.* *o\.* *box/i", $this->htmlEscape($this->getAddress()->getStreet(1))))
            {
                $carrierName = strtoupper(str_replace(" ", "", $this->getCarrierName($code)));
                if ($carrierName != "UNITEDSTATESPOSTALSERVICE")
                {
                    continue;
                }
            }
            */
         ?>

I had the same problem.

Remove "Free Shipping" configuration because you don't need it (you already have "Cart Price Rules").

When your customer qualifies for free shipping it happens based on "Flat Rate" not in "Free Shipping".