Its probably a bad resistor.
You have a bad blower motor resister.........
Should be behind the glove box. The blower motor speed resistor is located under the hood, on the firewall, passenger side, close to the blower motor.
how to change the blower motor
The blower motor is under the glove compartment
check the fueses check fueses
if it is the same number on it!!
In the dash under the glove box
No repairing those blower motors, replace it with a new one.
Loose connection or blower motor is bad
the blower motor relay is located next to the blower motor it is connected to the motor by a purple and black wires
down uner the glove box
Under the hood, passenger side firewall, close to the heater blower motor.