Also, keep in mind that the thermostat controls when the air goes on and off. If it is located in the living room it is using the temperature in the living room to control when it goes on and off. So if you close the vents in the living room, it will keep the heat on until the heat reaches the required temperature in the living room to shut off. This is also why you are having the problem of the bedroom being cold while the living room is warm, which happens in my house too.