You need to replace the blower motor resistor located near the glove box.
Check for a bad blower resistor at blower motor
bad blower,buy a good one and replace
when a blower motor only works on high, it is usually due to faulty resistor board. Should be located in the duct near the blower. the purpose of this is so the air blown by the blower keeps the resistors cool.
the resistor for the blower motor is busted blower works on high with out it
either the switch or the fan motor
Blower fan inoperative or only works on high speed.
you have a bare wire touching on your blower motor
More than likely the blower motor speed resistor burned out.
The blower speed resistor is burned out. It is located under the hood, on the firewall, passenger side, not far from the blower motor.
you need a new blower motor resistor
There is a resistor near the blower that is bad, known cause is high speed only.
If you are saying the Blower Motor only works on high, then your problem is a defective Blower Motor Resistor Pack. Replace it.