It usually shouldn't, but if it does, it should only stay like that for a few moments.
it needs a new blower motor resistor ....
Open hood . Disconnect blower module located near blower fan. Disconnect, if blower shuts off, repalce module
One reason a 2004 Monte Carlo heater motor blower may not work is low coolant. You can check the coolant level after the car has been turned off.
The heater blower motor is under the hood bolted to the heater plenum on the passenger side of the car.
The heater blower motor itself is located under the hood on the passenger side of the car.
The car heater is a vague question. The heater core is not fused, it is like a mini radiator. The blower motor for heat/AC is fused. The selector blower motor resistor is fused in line with blower motor. Now if you lost heat, the water pump is belt driven, not fused.
The most likely cause is a bad blower motor resistor.
check the blower motor resistor
Heater blower motor is defective and locked up, or possible short in the wiring.
Check a wiring diagram for your Bonneville (Mitchell, or Chilton) Most likely a blower relay stuck in on position.
if its a car, your head gasket may be blown. watch out for boiling coolant
Overheating at the Fan Switch merges contacts inside. Replace the switch and the problem will go away.