My heater stopped working this morning. Any ideas?

Hello, Inside the air ducts, there is a small door called a blend door. attached to the duct from the outside, an actuator turns the blend door, and changes the temperature of the air that is allowed to go to the vents. When the door or actuator fail, or the fuse for the actuator blows, the result can be that only one temperature of air exits the vents, regardless of the driver's request. Check your fuses first, then seek diagnostics for the actuator and blend door.