tHERES A RELAY BEHIND THE GLOVE BOX THAT BURNS OUT THAT MUST BE REPLACED.
Blown fuse.
The blower motor resistor is bad.
If by quit working you mean quit blowing, the things to troubleshoot are the blower motor, the blower motor resistor switch, or the blower motor speed selector switch. If by quit working you mean it only blows cold or warm air, the thermostat is probably stuck in the open position.
Could be, Blown fuse, Bad blower motor, Bad blower motor speed resistor, Bad blower switch,
Check you fuses..first
Your blower motor is going out. Be prepared to replace it soon or it will just quit working all together.
Blown fuse? Bad relay? Bad switch? Burned out motor?
Check fuse if the blower is not working. If it is then replace your heater core. if its not then replace your fan switch.
Because they are two separate units independent of each other.
Blower motor resistor is the most common problem. it is held in by 2 screws under the glovebox area. Easy to replace.
The resistor motor may have went out if the heater blower quit working on a 2004 F-250 Truck. The cost to replace the motor is approximately $200.
Blown fuse, defective blower motor resistor pack, defective blower motor, or defective fan speed switch.