Snack Attack Vending LLC is offering a Royal Vendors 550, 650, 660, 804 Refrigeration Relay. This is the latest updated version refrigeration relay. This relay is used in all Royal models. If your refrigeration unit starts up when door is closed and cools for a couple of hours and then gets warm or does not start up at all - more than likely relay needs replaced. The refrigeration relay is brand new from factory.