If your red light is flashing on the PC board for the freezer section,it means that there is a fault with one of the components in your freezer.It could be that your fan is not working so that only the bottom half of your freezer will work.Your heater element could be faulty causing it to ice up and stop the fan from working.Your door switch could be faulty or you could have a leak in the cooling system.Call a repair man that knows what he is doing as the the f640's can be quite temperamental.Good luck.