the resistor for the blower motor is busted blower works on high with out it
either the switch or the fan motor
replace the blower motor switch
check your blower fan. you may only be getting air thru your fresh air vent.
The blower motor works on only one speed. The blower motor resitor pack is defective and needs to be replaced. It is located on the blower housing in the engine compartment just below the blower motor.
bad blower motor
If you are saying that the blower motor only works on the high speed setting, then the Blower Motor Resistor is defective and needs replacing.
Defective Blower Motor Resistor Pack.
Loose connection or blower motor is bad
If the blower works on some speeds and not on others, you may not need a motor. Instead, you may only need a new blower motor resistor.
The blower motor speed resistor is burned out.
From my experience Toyota oil filter works great.
The wiring, switch or blower has failed.